The autumn effect: timing of physical dormancy break in seeds of two winter annual species of Geraniaceae by a stepwise process

PubMed Central

Gama-Arachchige, N. S.; Baskin, J. M.; Geneve, R. L.; Baskin, C. C.

2012-01-01

Background and Aims The involvement of two steps in the physical dormancy (PY)-breaking process previously has been demonstrated in seeds of Fabaceae and Convolvulaceae. Even though there is a claim for a moisture-controlled stepwise PY-breaking in some species of Geraniaceae, no study has evaluated the role of temperature in the PY-breaking process in this family. The aim of this study was to determine whether a temperature-controlled stepwise PY-breaking process occurs in seeds of the winter annuals Geranium carolinianum and G. dissectum. Methods Seeds of G. carolinianum and G. dissectum were stored under different temperature regimes to test the effect of storage temperature on PY-break. The role of temperature and moisture regimes in regulating PY-break was investigated by treatments simulating natural conditions. Greenhouse (non-heated) experiments on seed germination and burial experiments (outdoors) were carried out to determine the PY-breaking behaviour in the natural habitat. Key Results Irrespective of moisture conditions, sensitivity to the PY-breaking step in seeds of G. carolinianum was induced at temperatures ≥20 °C, and exposure to temperatures ≤20 °C made the sensitive seeds permeable. Sensitivity of seeds increased with time. In G. dissectum, PY-break occurred at temperatures ≥20 °C in a single step under constant wet or dry conditions and in two steps under alternate wet–dry conditions if seeds were initially kept wet. Conclusions Timing of seed germination with the onset of autumn can be explained by PY-breaking processes involving (a) two temperature-dependent steps in G. carolinianum and (b) one or two moisture-dependent step(s) along with the inability to germinate under high temperatures in G. dissectum. Geraniaceae is the third of 18 families with PY in which a two-step PY-breaking process has been demonstrated. PMID:22684684

Four minutes of in-class high-intensity interval activity improves selective attention in 9- to 11-year olds.

PubMed

Ma, Jasmin K; Le Mare, Lucy; Gurd, Brendon J

2015-03-01

The amount of time allocated to physical activity in schools is declining. Time-efficient physical activity solutions that demonstrate their impact on academic achievement-related outcomes are needed to prioritize physical activity within the school curricula. "FUNtervals" are 4-min, high-intensity interval activities that use whole-body actions to complement a storyline. The purpose of this study was to (i) explore whether FUNtervals can improve selective attention, an executive function posited to be essential for learning and academic success; and (ii) examine whether this relationship is predicted by students' classroom off-task behaviour. Seven grade 3-5 classes (n = 88) were exposed to a single-group, repeated cross-over design where each student's selective attention was compared between no-activity and FUNtervals days. In week 1, students were familiarized with the d2 test of attention and FUNterval activities, and baseline off-task behaviour was observed. In both weeks 2 and 3 students completed the d2 test of attention following either a FUNterval break or a no-activity break. The order of these breaks was randomized and counterbalanced between weeks. Neither motor nor passive off-task behaviour predicted changes in selective attention following FUNtervals; however, a weak relationship was observed for verbal off-task behaviour and improvements in d2 test performance. More importantly, students made fewer errors during the d2 test following FUNtervals. In supporting the priority of physical activity inclusion within schools, FUNtervals, a time efficient and easily implemented physical activity break, can improve selective attention in 9- to 11-year olds.

Observation of a discrete time crystal

NASA Astrophysics Data System (ADS)

Zhang, J.; Hess, P. W.; Kyprianidis, A.; Becker, P.; Lee, A.; Smith, J.; Pagano, G.; Potirniche, I.-D.; Potter, A. C.; Vishwanath, A.; Yao, N. Y.; Monroe, C.

2017-03-01

Spontaneous symmetry breaking is a fundamental concept in many areas of physics, including cosmology, particle physics and condensed matter. An example is the breaking of spatial translational symmetry, which underlies the formation of crystals and the phase transition from liquid to solid. Using the analogy of crystals in space, the breaking of translational symmetry in time and the emergence of a ‘time crystal’ was recently proposed, but was later shown to be forbidden in thermal equilibrium. However, non-equilibrium Floquet systems, which are subject to a periodic drive, can exhibit persistent time correlations at an emergent subharmonic frequency. This new phase of matter has been dubbed a ‘discrete time crystal’. Here we present the experimental observation of a discrete time crystal, in an interacting spin chain of trapped atomic ions. We apply a periodic Hamiltonian to the system under many-body localization conditions, and observe a subharmonic temporal response that is robust to external perturbations. The observation of such a time crystal opens the door to the study of systems with long-range spatio-temporal correlations and novel phases of matter that emerge under intrinsically non-equilibrium conditions.

Observation of a discrete time crystal.

PubMed

Zhang, J; Hess, P W; Kyprianidis, A; Becker, P; Lee, A; Smith, J; Pagano, G; Potirniche, I-D; Potter, A C; Vishwanath, A; Yao, N Y; Monroe, C

2017-03-08

Spontaneous symmetry breaking is a fundamental concept in many areas of physics, including cosmology, particle physics and condensed matter. An example is the breaking of spatial translational symmetry, which underlies the formation of crystals and the phase transition from liquid to solid. Using the analogy of crystals in space, the breaking of translational symmetry in time and the emergence of a 'time crystal' was recently proposed, but was later shown to be forbidden in thermal equilibrium. However, non-equilibrium Floquet systems, which are subject to a periodic drive, can exhibit persistent time correlations at an emergent subharmonic frequency. This new phase of matter has been dubbed a 'discrete time crystal'. Here we present the experimental observation of a discrete time crystal, in an interacting spin chain of trapped atomic ions. We apply a periodic Hamiltonian to the system under many-body localization conditions, and observe a subharmonic temporal response that is robust to external perturbations. The observation of such a time crystal opens the door to the study of systems with long-range spatio-temporal correlations and novel phases of matter that emerge under intrinsically non-equilibrium conditions.

Objectively measured sedentary time in youth with cerebral palsy compared with age-, sex-, and season-matched youth who are developing typically: an explorative study.

PubMed

Obeid, Joyce; Balemans, Astrid C J; Noorduyn, Stephen G; Gorter, Jan Willem; Timmons, Brian W

2014-08-01

Children with cerebral palsy (CP) demonstrate reduced physical activity levels compared with children with typical development. Sedentary behavior, including the duration and frequency of sedentary bouts, has not yet been objectively examined in this population but may have clinical implications for the development of secondary health complications. The aim of this study was to identify time spent sedentary and frequency of breaks interrupting sedentary time in youth with CP compared with youth without CP. It was hypothesized that individuals with CP would spend more hours sedentary than their peers and take fewer breaks to interrupt sedentary time. This was a cross-sectional, prospective study. A convenience sample of 17 ambulatory children with CP (15 boys and 2 girls) (mean age=13.0 years, SD=2.2) and 17 age-, sex-, and season-matched youth who were developing typically (TD group) (mean age=12.9 years, SD=2.5) wore an accelerometer over a 7-day period. Sedentary time (in minutes) and number of breaks from sedentary time, corrected for monitoring and sedentary time, respectively, were examined. Differences between groups were determined with an independent-samples t test. Children with CP engaged in significantly more sedentary time (X̅=47.5 min/h, SD=4.9) compared with the TD group (X̅=43.6 min/h, SD=4.2), with significantly fewer breaks from sedentary time (CP group: X̅=179, SD=70; TD group: X̅=232 breaks/h sedentary, SD=61). The sample included only ambulatory youth with CP, classified as Gross Motor Function Classification System levels I to III. Sedentary time was higher in the CP group and was characterized by less frequent breaks compared with the TD group. Future research should examine the extent to which sedentary time is associated with cardiovascular and metabolic risk in youth with CP. © 2014 American Physical Therapy Association.

Enhancing Physical Education with a Supplemental Physical Activity Program

ERIC Educational Resources Information Center

Adkins, Megan; Bice, Matthew R.; Heelan, Kate; Ball, James

2017-01-01

For decades, schools have played a pivotal role in providing physical activity opportunities to children. For many students, school-time physical activity serves as the primary source of activity, via activity clubs, classroom physical activity breaks, and family health awareness nights. The purpose of this article is to describe how three schools…

Sedentary patterns, physical activity and health-related physical fitness in youth: a cross-sectional study.

PubMed

Júdice, Pedro B; Silva, Analiza M; Berria, Juliane; Petroski, Edio L; Ekelund, Ulf; Sardinha, Luís B

2017-03-04

Strong evidence indicates that moderate-vigorous physical activity (MVPA) is positively associated with fitness in youth, independent of total sedentary-time. Sedentary-time appears negatively associated with fitness only when it replaces MVPA. However, whether different sedentary-patterns affect health-related fitness is unknown. The associations between MVPA and sedentary-patterns with physical fitness were examined in 2698 youths (1262 boys) aged 13.4 ± 2.28 years. Sedentary-time (counts · minute -1  < 100) and PA were objectively measured by accelerometry. Each break (≥100 counts · min -1  < 2295) in sedentary-time and the frequency of daily bouts in non-prolonged (<30 min) and prolonged (≥30 min) sedentary-time were determined. The FITNESSGRAM® test battery was used to assess fitness. A standardized fitness composite-score (z-score) was calculated by summing the individual z-scores of the five tests adjusted to age and sex. Positive associations between MVPA and fitness were observed in both boys (β = 0.013, 95% CI: 0.005; 0.021) and girls (β = 0.014, 95% CI: 0.006; 0.022), independent of sedentary-patterns. Modest associations were found for the breaks in sedentary-time with fitness (β = 0.026, 95% CI: 0.009; 0.042), independent of total sedentary-time and MVPA in boys. In girls, non-prolonged sedentary bouts were positively associated with fitness (β = 0.014, 95% CI: 0.003; 0.024), independent of total sedentary-time and MVPA. These results reinforce that, independent of the time and patterns of sedentary behavior, MVPA is consistently associated with fitness in youth. Modest and inconsistent associations were found for sedentary behaviors. Breaking-up sedentary-time in boys and non-prolonged sedentary bouts in girls were positively associated with fitness, independent of total sedentary-time and MVPA. In order to enhance youth's fitness, public health recommendations should primarily target MVPA, still, suggestion to reduce and break-up sedentary-time may also be considered.

Worksite physical activity breaks: Perspectives on feasibility of implementation.

PubMed

Bramante, Carolyn T; King, Maggie M; Story, Mary; Whitt-Glover, Melicia C; Barr-Anderson, Daheia J

2018-01-01

Worksites offer a unique opportunity to increase physical activity in persons with both active and sedentary lifestyles. The objective of this study was to examine employee and supervisor perspectives on feasibility and acceptability of 10-minute Instant Recess ® physical activity videos in the worksite. Convenience sample of public and private worksites in Minneapolis/St. Paul, MN. Employees (n = 187) at 13 worksites were recruited by a one-time email invitation to participate in a group Instant Recess break and complete a 15-question survey. One supervisor per site participated in a one-on-one interview to assess suggestions for feasibility of implementation. Likert-type survey responses were averaged per worksite and overall. Interview results were recorded, transcribed, and coded by two authors. Employees were extremely positive about enjoyment, increased productivity, comfort, and feasibility of doing Instant Recess at the same time and place every day (score = 4.29, 4.17, 4.25, and 4.37 out of 5, respectively). However, they did not feel comfortable leading an Instant Recess break (score = 2.68 out of 5). Supervisors voiced during the one-on-one interviews that they enjoyed Instant Recess (13 out of 13 supervisors), were enthusiastic about Instant Recess as a simple and cost-effective entry into worksite wellness (11 out of 13 supervisors), and felt that Instant Recess could be institutionalized by offering it daily at a set time and place (13 out of 13 supervisors). Employees and supervisors at various worksites believed that it is feasible and desirable to offer 10-minute physical activity breaks using videos during the workday.

Ergonomic principles and tools for best interdisciplinary psycho-physical stress prevention.

PubMed

Dal Cason, Dott Luigi

2012-01-01

The psycho-physical stress is a risk to all intents and purposes,finally acknowledged, it requires increasing attention. Measures forits protection are reflected in the appropriate application of organizational policies on a human scale, or in respect of the"macro-ergonomics". This work consists on several inter-disciplinary tools available to the proper prevention, outbreaks of work-related stress.During work, adequate rests are important to prevent work related physical and mental fatigue. The strategies for maintaining a healthy balance between work rate and work breaks, may differ depending on the individual, subjective habits and peculiarities related to the work environment. Resting does not necessarily mean "going to break". The break-time is important as the work-time. While the latter is regulated, the first is not always clearly defined, though necessary. Knowing the employment contract is the first step towards the implementation of their rights relating to periods of suspension from the activity of work is also essential for high performance working. Breathing exercises, massage therapy, biofeedback, role-playing are some of the tools used during work breaks to prevent mental and physical fatigue. At the end music has a rhythm by alternating strong and weak accents. If the musical notes represent the "vertical" trend of music (melody), figures and pauses, inserted into the rhythmic structure of the measure, regulate the duration of sounds over time and determine the "horizontal" trend of a song. Transferring this concept on work, is meant to understand, using a metaphor, the importance of respect of changes in both vertical and horizontal trends inside a cycle.

Effects of physical activity and breaks on mathematics engagement in adolescents.

PubMed

Owen, Katherine B; Parker, Philip D; Astell-Burt, Thomas; Lonsdale, Chris

2018-01-01

The purpose of this study was to determine whether physical activity has a positive relationship with school engagement regardless of the presence or absence of a recess or lunch break before the classroom lesson. Data were collected over three ten-week periods: January-April 2014 (Time 1), October-December 2014 (Time 2), and April-June 2015 (Time 3). A cohort of 2194 adolescents (mean age=13.40years, SD=.73) wore an accelerometer during the hour before a mathematics lesson and completed a questionnaire following the mathematics lesson to assess school engagement in that lesson. Linear mixed models indicated that moderate-intensity activity before a mathematics lesson had a positive linear relationship with cognitive engagement (β=.40, p<.05). Recess breaks before a mathematics lesson had a negative relationship with overall, behavioural, emotional, and cognitive engagement (β=-.18, p<.01, β=-.19, p<.01, β=-.13, p=.03, and β=-.13, p=.04, respectively). Promoting moderate-intensity activity prior to mathematics lessons could improve students' cognitive engagement. Educators should be aware that students tend to demonstrate the lowest levels of school engagement after recess breaks. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Time crystals: a review

NASA Astrophysics Data System (ADS)

Sacha, Krzysztof; Zakrzewski, Jakub

2018-01-01

Time crystals are time-periodic self-organized structures postulated by Frank Wilczek in 2012. While the original concept was strongly criticized, it stimulated at the same time an intensive research leading to propositions and experimental verifications of discrete (or Floquet) time crystals—the structures that appear in the time domain due to spontaneous breaking of discrete time translation symmetry. The struggle to observe discrete time crystals is reviewed here together with propositions that generalize this concept introducing condensed matter like physics in the time domain. We shall also revisit the original Wilczek’s idea and review strategies aimed at spontaneous breaking of continuous time translation symmetry.

Naturalness of Electroweak Symmetry Breaking

NASA Astrophysics Data System (ADS)

Espinosa, J. R.

2007-02-01

After revisiting the hierarchy problem of the Standard Model and its implications for the scale of New Physics, I consider the fine tuning problem of electroweak symmetry breaking in two main scenarios beyond the Standard Model: SUSY and Little Higgs models. The main conclusions are that New Physics should appear on the reach of the LHC; that some SUSY models can solve the hierarchy problem with acceptable residual fine tuning and, finally, that Little Higgs models generically suffer from large tunings, many times hidden.

A pilot study of physical activity and sedentary behavior distribution patterns in older women.

PubMed

Fortune, Emma; Mundell, Benjamin; Amin, Shreyasee; Kaufman, Kenton

2017-09-01

The study aims were to investigate free-living physical activity and sedentary behavior distribution patterns in a group of older women, and assess the cross-sectional associations with body mass index (BMI). Eleven older women (mean (SD) age: 77 (9) yrs) wore custom-built activity monitors, each containing a tri-axial accelerometer (±16g, 100Hz), on the waist and ankle for lab-based walking trials and 4 days in free-living. Daily active time, step counts, cadence, and sedentary break number were estimated from acceleration data. The sedentary bout length distribution and sedentary time accumulation pattern, using the Gini index, were investigated. Associations of the parameters' total daily values and coefficients of variation (CVs) of their hourly values with BMI were assessed using linear regression. The algorithm demonstrated median sensitivity, positive predictive value, and agreement values >98% and <1% mean error in cadence calculations with video identification during lab trials. Participants' sedentary bouts were found to be power law distributed with 56% of their sedentary time occurring in 20min bouts or longer. Meaningful associations were detectable in the relationships of total active time, step count, sedentary break number and their CVs with BMI. Active time and step counts had moderate negative associations with BMI while sedentary break number had a strong negative association. Active time, step count and sedentary break number CVs also had strong positive associations with BMI. The results highlight the importance of measuring sedentary behavior and suggest a more even distribution of physical activity throughout the day is associated with lower BMI. Copyright © 2017 Elsevier B.V. All rights reserved.

A comparison of work-related physical activity levels between inpatient and outpatient physical therapists: an observational cohort trial.

PubMed

Brewer, Wayne; Ogbazi, Raluchukwu; Ohl, Devan; Daniels, Jeffry; Ortiz, Alexis

2016-06-16

Physical therapists (PTs) work in a variety of healthcare settings with varied levels of physical activity demands placed on them. The purpose of this study is to compare the physical activity (PA) levels between PTs in inpatient versus outpatient environments for one work week using a cross-sectional design. Sixty-one PTs (30 inpatient, 31 outpatient) wore a tri-axial accelerometer and inclinometer for one work-week. The number steps-per-day, PA intensities, energy expenditures and postural positions adopted during the work day were recorded. Significantly longer amounts of time spent sitting was found for inpatient PTs regardless of the significantly higher number of steps-per-day. Outpatient PTs had a higher number of breaks from sedentary activity with those breaks being longer than the inpatient PTs. The percentage of time spent performing moderate-vigorous PA approached significance implying more time was spent performing these types of activities for outpatient PTs. The energy expenditures between the two groups of PTs were not different. This study compared the differences in physical activity levels between physical therapists who worked at inpatient versus outpatient environment as little is known about their activity levels. Inpatient physical therapists took more steps per day than outpatient physical therapists but the outpatient physical therapists were less sedentary and took more frequent and longer breaks from sedentary activities. The energy expenditures were similar between both types of therapists and this may be reflective of the gender and bodyweight differences between the groups that equalizes the energy expenditures. The findings of this study suggests that there are differences in the physical activity demands between inpatient and outpatient physical therapists. The results of this study may serve dual purposes: (1) employers may be able to more accurately describe the expected physical activity demands to future employees; (2) individuals tasked with preparing PTs to physically manage their work environment can outline training programs that are diverse based on the specific work environment of PTs.

Motivating Students to Be Active outside of Class: A Hierarchy for Independent Physical Activity

ERIC Educational Resources Information Center

Hill, Grant

2009-01-01

Despite the fact that children have an extraordinary amount of leisure time, students of all ages engage in too little physical activity. Opportunities for physical activity should be provided through recesses, lunch periods, organized fitness breaks, before- and after-school activity programs, and structured physical education classes. However,…

Effect of breaking up sedentary time with callisthenics on endothelial function.

PubMed

Carter, Sophie E; Gladwell, Valerie F

2017-08-01

Periods of prolonged sitting impairs endothelial function in lower limb conduit arteries, which is attenuated with physical activity breaks. The effect of activity breaks on upper limb arteries has not been examined. This study assessed changes in brachial artery endothelial function following either a prolonged sitting period or breaking up this sedentary time by performing sets of callisthenics exercises. Ten healthy participants (6 men) completed 2 conditions in a counterbalanced order: (a) 1-h 26-min sitting, or (b) breaking up this period every 20 min by performing a set of 5 callisthenics exercises. Brachial artery endothelial function was assessed via ultrasound using the flow-mediated dilation (FMD) technique prior to and following each condition, while brachial shear rate (SR) was acquired after each set of callisthenics. There was no significant change in FMD over time (P = 0.09) or between conditions (P = 0.12). Compared to sitting, brachial SR increased following each set of callisthenics, with a significant difference after the third break (Sit: 33.94 ± 12.79 s -1 ; Callisthenics: 57.16 ± 30.48 s -1 , P = 0.02). Alterations in SR in the upper limbs suggest callisthenics may be an effective intervention to break up sedentary time and attenuate the potentially deleterious effects of prolonged sitting on cardiovascular health.

Single-mode Laser by Parity-time Symmetry Breaking

DTIC Science & Technology

2014-11-21

solenoid -like Pds5B that reside in direct proximity to Wapl and the Smc3-Scc1 in- teraction interface (fig. S13), implying that Wapl and Pds5 control the...accepted 26 September 2014 10.1126/science.1256904 REPORTS ◥ OPTICS Single-mode laser by parity-time symmetry breaking Liang Feng,1* Zi Jing Wong,1...Ren-Min Ma,1* Yuan Wang,1,2 Xiang Zhang1,2† Effective manipulation of cavity resonant modes is crucial for emission control in laser physics and

Non-reciprocity in nonlinear elastodynamics

NASA Astrophysics Data System (ADS)

Blanchard, Antoine; Sapsis, Themistoklis P.; Vakakis, Alexander F.

2018-01-01

Reciprocity is a fundamental property of linear time-invariant (LTI) acoustic waveguides governed by self-adjoint operators with symmetric Green's functions. The break of reciprocity in LTI elastodynamics is only possible through the break of time reversal symmetry on the micro-level, and this can be achieved by imposing external biases, adding nonlinearities or allowing for time-varying system properties. We present a Volterra-series based asymptotic analysis for studying spatial non-reciprocity in a class of one-dimensional (1D), time-invariant elastic systems with weak stiffness nonlinearities. We show that nonlinearity is neither necessary nor sufficient for breaking reciprocity in this class of systems; rather, it depends on the boundary conditions, the symmetries of the governing linear and nonlinear operators, and the choice of the spatial points where the non-reciprocity criterion is tested. Extension of the analysis to higher dimensions and time-varying systems is straightforward from a mathematical point of view (but not in terms of new non-reciprocal physical phenomena), whereas the connection of non-reciprocity and time irreversibility can be studied as well. Finally, we show that suitably defined non-reciprocity measures enable optimization, and can provide physical understanding of the nonlinear effects in the dynamics, enabling one to establish regimes of "maximum nonlinearity." We highlight the theoretical developments by means of a numerical example.

Naturalness of Electroweak Symmetry Breaking while Waiting for the LHC

NASA Astrophysics Data System (ADS)

Espinosa, J. R.

2007-06-01

After revisiting the hierarchy problem of the Standard Model and its implications for the scale of New Physics, I consider the finetuning problem of electroweak symmetry breaking in several scenarios beyond the Standard Model: SUSY, Little Higgs and "improved naturalness" models. The main conclusions are that: New Physics should appear on the reach of the LHC; some SUSY models can solve the hierarchy problem with acceptable residual tuning; Little Higgs models generically suffer from large tunings, many times hidden; and, finally, that "improved naturalness" models do not generically improve the naturalness of the SM.

The Universe Adventure - The Plank Epoch

Science.gov Websites

Physics In the time before the first 10-44 seconds of the Universe, or the Planck Epoch, the laws of physics as we know them break down; the predictions of General Relativity become meaningless as distance physics models predict that during this epoch the four fundamental forces were combined into one unified

Examining the Knowledge and Capacity of Elementary Teachers to Implement Classroom Physical Activity Breaks

ERIC Educational Resources Information Center

Dinkel, Danae M.; Lee, Jung-Min; Schaffer, Connie

2016-01-01

This study examined teachers' zone of proximal development for classroom physical activity breaks by assessing teachers' knowledge and capacity for implementing classroom physical activity breaks. Five school districts of various sizes (n = 346 teachers) took part in a short online survey. Descriptive statistics were calculated and chi-square…

Physical Activity Opportunities during the School Day: Classroom Teachers' Perceptions of Using Activity Breaks in the Classroom

ERIC Educational Resources Information Center

McMullen, Jaimie; Kulinna, Pamela; Cothran, Donetta

2014-01-01

The purpose of this study was to explore classroom teachers' perceptions of incorporating physical activity breaks into their classroom and to determine specific features of preferred activity breaks. These perceptions are considered within the conceptual framework of Comprehensive School Physical Activity Program (CSPAP). Twelve elementary and…

Drop Tower Physics

ERIC Educational Resources Information Center

Dittrich, William A.

2014-01-01

The drop towers of yesteryear were used to make lead shot for muskets, as described in "The Physics Teacher" in April 2012. However, modern drop towers are essentially elevators designed so that the cable can "break" on demand, creating an environment with microgravity for a short period of time, currently up to nine seconds at…

Effects of surface wave breaking on the oceanic boundary layer

NASA Astrophysics Data System (ADS)

He, Hailun; Chen, Dake

2011-04-01

Existing laboratory studies suggest that surface wave breaking may exert a significant impact on the formation and evolution of oceanic surface boundary layer, which plays an important role in the ocean-atmosphere coupled system. However, present climate models either neglect the effects of wave breaking or treat them implicitly through some crude parameterization. Here we use a one-dimensional ocean model (General Ocean Turbulence Model, GOTM) to investigate the effects of wave breaking on the oceanic boundary layer on diurnal to seasonal time scales. First a set of idealized experiments are carried out to demonstrate the basic physics and the necessity to include wave breaking. Then the model is applied to simulating observations at the northern North Sea and the Ocean Weather Station Papa, which shows that properly accounting for wave breaking effects can improve model performance and help it to successfully capture the observed upper ocean variability.

Physical activity breaks and facilities in US secondary schools

PubMed Central

Hood, Nancy E.; Colabianchi, Natalie; Terry-McElrath, Yvonne M.; O’Malley, Patrick M.; Johnston, Lloyd D.

2014-01-01

BACKGROUND Research on physical activity breaks and facilities (indoor and outdoor) in secondary schools is relatively limited. METHODS School administrators and students in nationally representative samples of 8th (middle school) and 10th/12th grade (high school) students were surveyed annually from 2008-09 through 2011-12. School administrators reported information about physical activity breaks and facilities. Students self-reported height, weight, and physical activity. RESULTS The prevalence of physical activity breaks and indoor and outdoor facilities (dichotomized by median split) differed significantly by region of the country, school size, student race/ethnicity, and school socioeconomic status (SES). Breaks were associated with lower odds of overweight (adjusted odds ratio (AOR) = 0.91, 95% confidence interval (CI): 0.83-1.00) and obesity (AOR = 0.86, 95% CI: 0.75-0.99) among middle school students. Among low-SES middle school students and schools, higher indoor facilities were associated with lower rates of overweight and obesity. Among high school students, higher indoor and outdoor facilities were associated with 19%-42% higher odds of moderate-to-vigorous physical activity. CONCLUSIONS Physical activity breaks and school facilities may help to address high rates of overweight/obesity and low physical activity levels among secondary students, especially lower-SES students. Students in all schools should have equal access to these resources. PMID:25274169

Strong-Isospin-Breaking Correction to the Muon Anomalous Magnetic Moment from Lattice QCD at the Physical Point

NASA Astrophysics Data System (ADS)

Chakraborty, B.; Davies, C. T. H.; Detar, C.; El-Khadra, A. X.; Gámiz, E.; Gottlieb, Steven; Hatton, D.; Koponen, J.; Kronfeld, A. S.; Laiho, J.; Lepage, G. P.; Liu, Yuzhi; MacKenzie, P. B.; McNeile, C.; Neil, E. T.; Simone, J. N.; Sugar, R.; Toussaint, D.; van de Water, R. S.; Vaquero, A.; Fermilab Lattice, Hpqcd,; Milc Collaborations

2018-04-01

All lattice-QCD calculations of the hadronic-vacuum-polarization contribution to the muon's anomalous magnetic moment to date have been performed with degenerate up- and down-quark masses. Here we calculate directly the strong-isospin-breaking correction to aμHVP for the first time with physical values of mu and md and dynamical u , d , s , and c quarks, thereby removing this important source of systematic uncertainty. We obtain a relative shift to be applied to lattice-QCD results obtained with degenerate light-quark masses of δ aμHVP ,mu≠md=+1.5 (7 )% , in agreement with estimates from phenomenology.

Strong-Isospin-Breaking Correction to the Muon Anomalous Magnetic Moment from Lattice QCD at the Physical Point

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, B.; Davies, C. T. H.; DeTar, C.

All lattice-QCD calculations of the hadronic-vacuum-polarization contribution to the muon’s anomalous magnetic moment to date have been performed with degenerate up- and down-quark masses. Here we calculate directly the strong-isospin-breaking correction tomore » $${a}_{{\\mu}}^{\\mathrm{HVP}}$$ for the first time with physical values of $${m}_{u}$$ and $${m}_{d}$$ and dynamical $u$, $d$, $s$, and $c$ quarks, thereby removing this important source of systematic uncertainty. We obtain a relative shift to be applied to lattice-QCD results obtained with degenerate light-quark masses of $${\\delta}{a}_{{\\mu}}^{\\mathrm{HVP},{m}_{u}{\

Strong-Isospin-Breaking Correction to the Muon Anomalous Magnetic Moment from Lattice QCD at the Physical Point

DOE PAGES

Chakraborty, B.; Davies, C. T. H.; DeTar, C.; ...

2018-04-12

All lattice-QCD calculations of the hadronic-vacuum-polarization contribution to the muon’s anomalous magnetic moment to date have been performed with degenerate up- and down-quark masses. Here we calculate directly the strong-isospin-breaking correction tomore » $${a}_{{\\mu}}^{\\mathrm{HVP}}$$ for the first time with physical values of $${m}_{u}$$ and $${m}_{d}$$ and dynamical $u$, $d$, $s$, and $c$ quarks, thereby removing this important source of systematic uncertainty. We obtain a relative shift to be applied to lattice-QCD results obtained with degenerate light-quark masses of $${\\delta}{a}_{{\\mu}}^{\\mathrm{HVP},{m}_{u}{\

Ian in the Department

NASA Astrophysics Data System (ADS)

Wheater, J. F.

When Ian came to Oxford almost a decade ago he brought with him experience of very different institutions but also respect and sensitivity towards this one. It did not take him long to appreciate the fundamental good sense of the English custom of the coffee break at 11 and the tea break at 4. But Ian was a dynamo and we learned that the true purpose of the coffee break is to initiate a physics discussion which, had it not been for the intervention of lunch, would still have been going on at tea time. Ian was a man at ease with himself and forever generous to others. He was an ever-present inhabitant of the Discussion Room in Keble Road and loved to include anyone who was interested in the subject under consideration. Students, post-docs, staff; we have spent many happy hours exploring the magical world of theoretical physics in Ian's company…

Break for Physical Activity: Incorporating Classroom-Based Physical Activity Breaks into Preschools

ERIC Educational Resources Information Center

Wadsworth, Danielle D.; Robinson, Leah E.; Beckham, Karen; Webster, Kip

2012-01-01

Engaging in moderate-to-vigorous physical activity is essential to lifelong health and wellness. Physical activity behaviors established in early childhood relate to physical activity behaviors in later years. However, research has shown that children are adopting more sedentary behaviors. Incorporating structured and planned physical activity…

Stable and unstable singularities in the unforced Hele-Shaw cell

DOE Office of Scientific and Technical Information (OSTI.GOV)

Almgren, R.; Bertozzi, A.; Brenner, M.P.

We study singularity formation in the lubrication model for the unforced Hele-Shaw system, describing the breaking in two of a fluid droplet confined between two narrowly spaced glass plates. By varying the initial data, we exhibit four different scenarios: (1) the droplet breaks in finite time, with two pinch points moving toward each other and merging at the singular time; (2) the droplet breaks in finite time, with two asymmetric pinch points propagating away from each other; (3) the droplet breaks in finite time, with a single symmetric pinch point; or (4) the droplet relaxes to a stable equilibrium shapemore » without a finite time breakup. Each of the three singular scenarios has a self-similar structure with different scaling laws; the first scenario has not been observed before in other Hele-Shaw studies. We demonstrate instabilities of the second and third scenarios, in which the solution changes its behavior at a thickness that can be arbitrarily small depending on the initial condition. These transitions can be identified by examining the structure of the solution in the intermediate scaling region. {copyright} {ital 1996 American Institute of Physics.}« less

Accelerometer-derived physical activity and sedentary time by cancer type in the United States.

PubMed

Thraen-Borowski, Keith M; Gennuso, Keith P; Cadmus-Bertram, Lisa

2017-01-01

The 2003-2004 and 2005-2006 cycles of the National Health and Nutrition Examination Survey (NHANES) were among the first population-level studies to incorporate objectively measured physical activity and sedentary behavior, allowing for greater understanding of these behaviors. However, there has yet to be a comprehensive examination of these data in cancer survivors, including short- and long-term survivors of all cancer types. Therefore, the purpose of this analysis was to use these data to describe activity behaviors in short- and long-term cancer survivors of various types. A secondary aim was to compare activity patterns of cancer survivors to that of the general population. Cancer survivors (n = 508) and age-matched individuals not diagnosed with cancer (n = 1,016) were identified from a subsample of adults with activity measured by accelerometer. Physical activity and sedentary behavior were summarized across cancer type and demographics; multivariate regression was used to evaluate differences between survivors and those not diagnosed with cancer. On average, cancer survivors were 61.4 (95% CI: 59.6, 63.2) years of age; 57% were female. Physical activity and sedentary behavior patterns varied by cancer diagnosis, demographic variables, and time since diagnosis. Survivors performed 307 min/day of light-intensity physical activity (95% CI: 295, 319), 16 min/day of moderate-vigorous intensity activity (95% CI: 14, 17); only 8% met physical activity recommendations. These individuals also reported 519 (CI: 506, 532) minutes of sedentary time, with 86 (CI: 84, 88) breaks in sedentary behavior per day. Compared to non-cancer survivors, after adjustment for potential confounders, survivors performed less light-intensity activity (P = 0.01), were more sedentary (P = 0.01), and took fewer breaks in sedentary time (P = 0.04), though there were no differences in any other activity variables. These results suggest that cancer survivors are insufficiently active. Relative to adults of similar age not diagnosed with cancer, they engage in more sedentary time with fewer breaks. As such, sedentary behavior and light-intensity activity may be important intervention targets, particularly for those for whom moderate-to-vigorous activity is not well accepted.

Static non-reciprocity in mechanical metamaterials.

PubMed

Coulais, Corentin; Sounas, Dimitrios; Alù, Andrea

2017-02-23

Reciprocity is a general, fundamental principle governing various physical systems, which ensures that the transfer function-the transmission of a physical quantity, say light intensity-between any two points in space is identical, regardless of geometrical or material asymmetries. Breaking this transmission symmetry offers enhanced control over signal transport, isolation and source protection. So far, devices that break reciprocity (and therefore show non-reciprocity) have been mostly considered in dynamic systems involving electromagnetic, acoustic and mechanical wave propagation associated with fields varying in space and time. Here we show that it is possible to break reciprocity in static systems, realizing mechanical metamaterials that exhibit vastly different output displacements under excitation from different sides, as well as one-way displacement amplification. This is achieved by combining large nonlinearities with suitable geometrical asymmetries and/or topological features. In addition to extending non-reciprocity and isolation to statics, our work sheds light on energy propagation in nonlinear materials with asymmetric crystalline structures and topological properties. We anticipate that breaking reciprocity will open avenues for energy absorption, conversion and harvesting, soft robotics, prosthetics and optomechanics.

BOOK REVIEW: Symmetry Breaking

NASA Astrophysics Data System (ADS)

Ryder, L. H.

2005-11-01

One of the most fruitful and enduring advances in theoretical physics during the last half century has been the development of the role played by symmetries. One needs only to consider SU(3) and the classification of elementary particles, the Yang Mills enlargement of Maxwell's electrodynamics to the symmetry group SU(2), and indeed the tremendous activity surrounding the discovery of parity violation in the weak interactions in the late 1950s. This last example is one of a broken symmetry, though the symmetry in question is a discrete one. It was clear to Gell-Mann, who first clarified the role of SU(3) in particle physics, that this symmetry was not exact. If it had been, it would have been much easier to discover; for example, the proton, neutron, Σ, Λ and Ξ particles would all have had the same mass. For many years the SU(3) symmetry breaking was assigned a mathematical form, but the importance of this formulation fell away when the quark model began to be taken seriously; the reason the SU(3) symmetry was not exact was simply that the (three, in those days) quarks had different masses. At the same time, and in a different context, symmetry breaking of a different type was being investigated. This went by the name of `spontaneous symmetry breaking' and its characteristic was that the ground state of a given system was not invariant under the symmetry transformation, though the interactions (the Hamiltonian, in effect) was. A classic example is ferromagnetism. In a ferromagnet the atomic spins are aligned in one direction only—this is the ground state of the system. It is clearly not invariant under a rotation, for that would change the ground state into a (similar but) different one, with the spins aligned in a different direction; this is the phenomenon of a degenerate vacuum. The contribution of the spin interaction, s1.s2, to the Hamiltonian, however, is actually invariant under rotations. As Coleman remarked, a little man living in a ferromagnet would have to be rather clever to recognize that the particle interactions were rotationally invariant. Nambu and Goldstone showed that the spontaneous breakdown of a (continuous) symmetry implied the existence of massless scalar particles, referred to as Nambu Goldstone bosons, or simply Goldstone bosons. Meanwhile Anderson, in his study of (non-relativistic) superconductivity, showed that the exclusion of magnetic flux (Meissner effect) corresponds to a finite range for the electromagnetic field and hence to a `massive photon'. In a relativistic context Englert, Brout, Guralnik and more particularly Higgs showed that a spontaneous breaking of a gauge symmetry resulted in a massive, instead of a massless, gauge particle and no Goldstone particle; in the jargon of the day, the massless gauge particle had `eaten' the massless Goldstone boson and become massive; exactly Anderson's observation. It is this phenomenon which has been invoked so successfully to explain the masses of the W and Z bosons of weak interactions. Spontaneous symmetry breaking, therefore, has played a major role in the development of the Standard Model of particle physics, and it has also proved an important tool in condensed matter physics, for example in the understanding of phase transitions. At the same time, however, in the understanding of most (or all) particle physicists, and perhaps also condensed matter physicists, the notion of spontaneous symmetry breaking has been inexorably linked to that of a degenerate vacuum. This is the background and the starting point for Strocchi's book. Recognizing the power and importance of the concept of spontaneous symmetry breaking in theoretical physics, he defines it in a more refined and general way than usual. `Despite the many popular accounts', he writes, `the phenomenon of spontaneous symmetry breaking is deep and subtle and it is not without [reason] that it has been fully understood only in recent times.' Strocchi's main emphasis is on the fact that the loss of symmetric behaviour requires both the existence of non-symmetric ground states and the infinite extension of the system. The book is divided into two parts, treating respectively the classical and quantum regimes. In classical field theory the symmetry breaking is explained in terms of the occurrence of disjoint sectors, or different phases, of a physical system. In the quantum regime the mechanism is characterized by a symmetry breaking order parameter, for which non-perturbative criteria are discussed, following the work of Wightman, in contrast to the usual Goldstone perturbative strategy. Strocchi's main interest is in condensed matter, rather than particle, physics, and the topics he covers include spin systems, Fermi and Bose gases and finite temperature field theory. The book is based on lectures given over a number of years. It is written in a pleasing style at a level suitable for graduate students in theoretical physics. While mathematically proper, it is not forbidding for a physics readership; the author is always aware this subject is a branch of physics. It should make profitable reading for many theoretical physicists.

Social and physical aggression trajectories from childhood through late adolescence: Predictors of psychosocial maladjustment at age 18.

PubMed

Ehrenreich, Samuel E; Beron, Kurt J; Underwood, Marion K

2016-03-01

This research examined whether following social and physical aggression trajectories across Grades 3-12 predicted psychological maladjustment. Teachers rated participants' (n = 287, 138 boys) aggressive behavior at the end of each school year. Following the 12th grade, psychosocial outcomes were measured: rule-breaking behaviors, internalizing symptoms, and narcissistic and borderline personality features. Following the highest social aggression trajectory predicted rule-breaking behavior; the medium social aggression trajectory was not a significant predictor of any outcome. Following the highest physical aggression trajectory predicted rule-breaking, internalizing symptoms, and narcissism, whereas the medium physical aggression trajectory predicted rule-breaking and internalizing symptoms. (c) 2016 APA, all rights reserved).

Social and physical aggression trajectories from childhood through late adolescence: Predictors of psychosocial maladjustment at age 18

PubMed Central

Ehrenreich, Samuel E.; Beron, Kurt J.; Underwood, Marion K.

2016-01-01

This research examined whether following social and physical aggression trajectories across grades 3–12 predicted psychological maladjustment. Teachers rated participants’ (n=287, 138 boys) aggressive behavior at the end of each school year. Following the 12th grade, psychosocial outcomes were measured: rule-breaking behaviors, internalizing symptoms, and narcissistic and borderline personality features. Following the highest social aggression trajectory predicted rule-breaking behavior; the medium social aggression trajectory was not a significant predictor of any outcome. Following the highest physical aggression trajectory predicted rule-breaking, internalizing symptoms and narcissism, whereas the medium physical aggression trajectory predicted rule-breaking and internalizing symptoms. PMID:26891018

Factors affecting fuel break effectiveness in the control of large fires on the Los Padres National Forest, California

USGS Publications Warehouse

Syphard, Alexandra D.; Keeley, Jon E.; Brennan, Teresa J.

2011-01-01

As wildfires have increased in frequency and extent, so have the number of homes developed in the wildland-urban interface. In California, the predominant approach to mitigating fire risk is construction of fuel breaks, but there has been little empirical study of their role in controlling large fires.We constructed a spatial database of fuel breaks on the Los Padres National Forest in southern California to better understand characteristics of fuel breaks that affect the behaviour of large fires and to map where fires and fuel breaks most commonly intersect. We evaluated whether fires stopped or crossed over fuel breaks over a 28-year period and compared the outcomes with physical characteristics of the sites, weather and firefighting activities during the fire event. Many fuel breaks never intersected fires, but others intersected several, primarily in historically fire-prone areas. Fires stopped at fuel breaks 46% of the time, almost invariably owing to fire suppression activities. Firefighter access to treatments, smaller fires and longer fuel breaks were significant direct influences, and younger vegetation and fuel break maintenance indirectly improved the outcome by facilitating firefighter access. This study illustrates the importance of strategic location of fuel breaks because they have been most effective where they provided access for firefighting activities.

Strong-Isospin-Breaking Correction to the Muon Anomalous Magnetic Moment from Lattice QCD at the Physical Point.

PubMed

Chakraborty, B; Davies, C T H; DeTar, C; El-Khadra, A X; Gámiz, E; Gottlieb, Steven; Hatton, D; Koponen, J; Kronfeld, A S; Laiho, J; Lepage, G P; Liu, Yuzhi; Mackenzie, P B; McNeile, C; Neil, E T; Simone, J N; Sugar, R; Toussaint, D; Van de Water, R S; Vaquero, A

2018-04-13

All lattice-QCD calculations of the hadronic-vacuum-polarization contribution to the muon's anomalous magnetic moment to date have been performed with degenerate up- and down-quark masses. Here we calculate directly the strong-isospin-breaking correction to a_{μ}^{HVP} for the first time with physical values of m_{u} and m_{d} and dynamical u, d, s, and c quarks, thereby removing this important source of systematic uncertainty. We obtain a relative shift to be applied to lattice-QCD results obtained with degenerate light-quark masses of δa_{μ}^{HVP,m_{u}≠m_{d}}=+1.5(7)%, in agreement with estimates from phenomenology.

Intra-population level variation in thresholds for physical dormancy-breaking temperature

PubMed Central

Liyanage, Ganesha S.; Ooi, Mark K. J.

2015-01-01

Background and Aims Intra-population variation in seed dormancy is an advantage for population persistence in unpredictable environments. The important role played by physically dormant species in these habitats makes understanding the level of variation in their dormancy a key ecological question. Heat produced in the soil is the major dormancy-breaking stimulus and, in fire prone ecosystems, soil temperatures generated by fire may vary spatially and over time. While many studies have investigated variation in initial dormancy, a measure that is of little value in fire-prone ecosystems, where initial dormancy levels are uniformly high, intra-population variation in dormancy-breaking temperature thresholds has never been quantified. This study predicted that species would display variation in dormancy-breaking temperature thresholds within populations, and investigated whether this variation occurred between individual plants from the same maternal environment. Methods The intra-population variation in dormancy-breaking thresholds of five common physically dormant shrub species (family Fabaceae) from fire-prone vegetation in south-eastern Australia was assessed using heat treatments and germination trials. Replicate batches of seeds from each of four maternal plants of Dillwynia floribunda, Viminaria juncea, Bossiaea heterophylla, Aotus ericoides and Acacia linifolia were treated at 40, 60, 80, 100 and 120 °C. Key Results Dormancy-breaking response to heat treatments varied significantly among individual plants for all species, with some individuals able to germinate after heating at low temperatures and others restricting germination to temperatures that only occur as a result of high-severity fires. Germination rate (T50) varied among individuals of three species. Conclusions Variation detected among individuals that were in close proximity to each other indicates that strong differences in dormancy-breaking temperature thresholds occur throughout the broader population. Differences found at the individual plant level could contribute to subsequent variation within the seed bank, providing a bet-hedging strategy, and represent a mechanism for increasing the probability of population persistence in the face of fire regime variability. PMID:25997432

Symmetries in Physics

NASA Astrophysics Data System (ADS)

Brading, Katherine; Castellani, Elena

2010-01-01

Preface; Copyright acknowledgements; List of contributors; 1. Introduction; Part I. Continuous Symmetries: 2. Classic texts: extracts from Weyl and Wigner; 3. Review paper: On the significance of continuous symmetry to the foundations of physics C. Martin; 4. The philosophical roots of the gauge principle: Weyl and transcendental phenomenological idealism T. Ryckman; 5. Symmetries and Noether's theorems K. A. Brading and H. R. Brown; 6. General covariance, gauge theories, and the Kretschmann objection J. Norton; 7. The interpretation of gauge symmetry M. Redhead; 8. Tracking down gauge: an ode to the constrained Hamiltonian formalism J. Earman; 9. Time-dependent symmetries: the link between gauge symmetries and indeterminism D. Wallace; 10. A fourth way to the Aharanov-Bohm effect A. Nounou; Part II. Discrete Symmetries: 11. Classic texts: extracts from Lebniz, Kant and Black; 12. Review paper: Understanding permutation symmetry S. French and D. Rickles; 13. Quarticles and the identity of discernibles N. Hugget; 14. Review paper: Handedness, parity violation, and the reality of space O. Pooley; 15. Mirror symmetry: what is it for a relational space to be orientable? N. Huggett; 16. Physics and Leibniz's principles S. Saunders; Part III. Symmetry Breaking: 17: Classic texts: extracts from Curie and Weyl; 18. Extract from G. Jona-Lasinio: Cross-fertilization in theoretical physics: the case of condensed matter and particle physics G. Jona-Lasinio; 19. Review paper: On the meaning of symmetry breaking E. Castellani; 20. Rough guide to spontaneous symmetry breaking J. Earman; 21. Spontaneous symmetry breaking: theoretical arguments and philosophical problems M. Morrison; Part IV. General Interpretative Issues: 22. Classic texts: extracts from Wigner; 23. Symmetry as a guide to superfluous theoretical structure J. Ismael and B. van Fraassen; 24. Notes on symmetries G. Belot; 25. Symmetry, objectivity, and design P. Kosso; 26. Symmetry and equivalence E. Castellani.

Symmetries in Physics

NASA Astrophysics Data System (ADS)

Brading, Katherine; Castellani, Elena

2003-12-01

Preface; Copyright acknowledgements; List of contributors; 1. Introduction; Part I. Continuous Symmetries: 2. Classic texts: extracts from Weyl and Wigner; 3. Review paper: On the significance of continuous symmetry to the foundations of physics C. Martin; 4. The philosophical roots of the gauge principle: Weyl and transcendental phenomenological idealism T. Ryckman; 5. Symmetries and Noether's theorems K. A. Brading and H. R. Brown; 6. General covariance, gauge theories, and the Kretschmann objection J. Norton; 7. The interpretation of gauge symmetry M. Redhead; 8. Tracking down gauge: an ode to the constrained Hamiltonian formalism J. Earman; 9. Time-dependent symmetries: the link between gauge symmetries and indeterminism D. Wallace; 10. A fourth way to the Aharanov-Bohm effect A. Nounou; Part II. Discrete Symmetries: 11. Classic texts: extracts from Lebniz, Kant and Black; 12. Review paper: Understanding permutation symmetry S. French and D. Rickles; 13. Quarticles and the identity of discernibles N. Hugget; 14. Review paper: Handedness, parity violation, and the reality of space O. Pooley; 15. Mirror symmetry: what is it for a relational space to be orientable? N. Huggett; 16. Physics and Leibniz's principles S. Saunders; Part III. Symmetry Breaking: 17: Classic texts: extracts from Curie and Weyl; 18. Extract from G. Jona-Lasinio: Cross-fertilization in theoretical physics: the case of condensed matter and particle physics G. Jona-Lasinio; 19. Review paper: On the meaning of symmetry breaking E. Castellani; 20. Rough guide to spontaneous symmetry breaking J. Earman; 21. Spontaneous symmetry breaking: theoretical arguments and philosophical problems M. Morrison; Part IV. General Interpretative Issues: 22. Classic texts: extracts from Wigner; 23. Symmetry as a guide to superfluous theoretical structure J. Ismael and B. van Fraassen; 24. Notes on symmetries G. Belot; 25. Symmetry, objectivity, and design P. Kosso; 26. Symmetry and equivalence E. Castellani.

Physical Evaluation of Cleaning Performance: We Are Only Fooling Ourselves

NASA Technical Reports Server (NTRS)

Pratz, Earl; McCool, A. (Technical Monitor)

2000-01-01

Surface cleaning processes are normally evaluated using visual physical properties such as discolorations, streaking, staining and water-break-free conditions. There is an assumption that these physical methods will evaluate all surfaces all the time for all subsequent operations. We have found that these physical methods are lacking in sensitivity and selectivity with regard to surface residues and subsequent process performance. We will report several conditions where evaluations using visual physical properties are lacking. We will identify possible alternative methods and future needs for surface evaluations.

Barriers to Physical Activity in a Mass Transit Population: A Qualitative Study.

PubMed

Das, Bhibha M; Petruzzello, Steven J

2016-01-01

The physical inactivity epidemic continues be one of the greatest public health challenges in contemporary society in the United States. The transportation industry is at greater risk of physical inactivity, compared with individuals in other sectors of the workforce. The aim of this study was to use the Nominal Group Technique, a focus group technique, to examine mass transit employees' perceptions of the barriers to physical activity at their worksite. Three focus groups (n = 31) were conducted to examine mass transit employees' perceptions of barriers to physical activity at the worksite. Salient barriers included (1) changing work schedules, (2) poor weather conditions, and (3) lack of scheduled and timely breaks. Findings were consistent with previous research demonstrating shift work, poor weather, and lack of breaks can negatively impact mass transit employees' ability to be physically active. Although physical activity barriers for this population have been consistent for the last 20 years, public health practice and policy have not changed to address these barriers. Future studies should include conducing focus groups stratified by job classification (eg, operators, maintenance, and clerical) along with implementing and evaluating worksite-based physical activity interventions and policy changes.

Spontaneous breaking of discrete symmetries in QCD on a small volume

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lucini, B.; Patella, A.; Pica, C.

2007-11-20

In a compact space with non-trivial cycles, for sufficiently small values of the compact dimensions, charge conjugation (C), spatial reflection (P) and time reversal (J) are spontaneously broken in QCD. The order parameter for the symmetry breaking is the trace of the Wilson line wrapping around the compact dimension, which acquires an imaginary part in the broken phase. We show that a physical signature for the symmetry breaking is a persistent baryonic current wrapping in the compact directions. The existence of such a current is derived analytically at first order in perturbation theory and confirmed in the non-perturbative regime bymore » lattice simulations.« less

Fainting

MedlinePlus

... sure kids: drink plenty of fluids, especially in hot weather or during physical activity take frequent breaks and move around as much as possible when sitting or standing for long periods of time slowly breathe into a paper bag when they are anxious and breathing too ...

Simulation of breaking waves using the high-order spectral method with laboratory experiments: Wave-breaking onset

NASA Astrophysics Data System (ADS)

Seiffert, Betsy R.; Ducrozet, Guillaume; Bonnefoy, Félicien

2017-11-01

This study investigates a wave-breaking onset criteria to be implemented in the non-linear potential flow solver HOS-NWT. The model is a computationally efficient, open source code, which solves for the free surface in a numerical wave tank using the High-Order Spectral (HOS) method. The goal of this study is to determine the best method to identify the onset of random single and multiple breaking waves over a large domain at the exact time they occur. To identify breaking waves, a breaking onset criteria based on the ratio of local energy flux velocity to the local crest velocity, introduced by Barthelemy et al. (2017) is selected. The breaking parameter is uniquely applied in the numerical model in that calculations of the breaking onset criteria ratio are not made only at the location of the wave crest, but at every point in the domain and at every time step. This allows the model to calculate the onset of a breaking wave the moment it happens, and without knowing anything about the wave a priori. The application of the breaking criteria at every point in the domain and at every time step requires the phase velocity to be calculated instantaneously everywhere in the domain and at every time step. This is achieved by calculating the instantaneous phase velocity using the Hilbert transform and dispersion relation. A comparison between more traditional crest-tracking techniques shows the calculation of phase velocity using Hilbert transform at the location of the breaking wave crest provides a good approximation of crest velocity. The ability of the selected wave breaking criteria to predict single and multiple breaking events in two dimensions is validated by a series of large-scale experiments. Breaking waves are generated by energy focusing and modulational instability methods, with a wide range of primary frequencies. Steep irregular waves which lead to breaking waves, and irregular waves with an energy focusing wave superimposed are also generated. This set of waves provides a wide range of breaking-wave strengths, types and scales for validation of the model. A comparison of calculations made using HOS-NWT with experimental measurements show that the model is successful at predicting the occurrence of wave breaking, as well as accurately calculating breaking onset time and location. Although the current study is limited to a unidirectional wave field, the success of the wave-breaking model presented provides the basis for application of the model in a multidirectional wave field. By including wave breaking onset with the addition of an appropriate energy dissipation model into HOS-NWT, we can increase the application range of the model, as well as decrease the occurrence of numerical instabilities that are associated with breaking waves in a potential flow solver. An accurate description of the wave field is useful for predicting the dynamic response of offshore vessels and marine renewable energy devices, predicting loads on marine structures and the general physics of ocean waves, for example.

Ultrafast dynamics of vibrational symmetry breaking in a charge-ordered nickelate

PubMed Central

Coslovich, Giacomo; Kemper, Alexander F.; Behl, Sascha; Huber, Bernhard; Bechtel, Hans A.; Sasagawa, Takao; Martin, Michael C.; Lanzara, Alessandra; Kaindl, Robert A.

2017-01-01

The ability to probe symmetry-breaking transitions on their natural time scales is one of the key challenges in nonequilibrium physics. Stripe ordering represents an intriguing type of broken symmetry, where complex interactions result in atomic-scale lines of charge and spin density. Although phonon anomalies and periodic distortions attest the importance of electron-phonon coupling in the formation of stripe phases, a direct time-domain view of vibrational symmetry breaking is lacking. We report experiments that track the transient multi-terahertz response of the model stripe compound La1.75Sr0.25NiO4, yielding novel insight into its electronic and structural dynamics following an ultrafast optical quench. We find that although electronic carriers are immediately delocalized, the crystal symmetry remains initially frozen—as witnessed by time-delayed suppression of zone-folded Ni–O bending modes acting as a fingerprint of lattice symmetry. Longitudinal and transverse vibrations react with different speeds, indicating a strong directionality and an important role of polar interactions. The hidden complexity of electronic and structural coupling during stripe melting and formation, captured here within a single terahertz spectrum, opens new paths to understanding symmetry-breaking dynamics in solids. PMID:29202025

Ultrafast dynamics of vibrational symmetry breaking in a charge-ordered nickelate

DOE PAGES

Coslovich, Giacomo; Kemper, Alexander F.; Behl, Sascha; ...

2017-11-24

The ability to probe symmetry-breaking transitions on their natural time scales is one of the key challenges in nonequilibrium physics. Stripe ordering represents an intriguing type of broken symmetry, where complex interactions result in atomic-scale lines of charge and spin density. Although phonon anomalies and periodic distortions attest the importance of electron-phonon coupling in the formation of stripe phases, a direct time-domain view of vibrational symmetry breaking is lacking. We report experiments that track the transient multi-terahertz response of the model stripe compound La 1.75Sr 0.25NiO 4, yielding novel insight into its electronic and structural dynamics following an ultrafast opticalmore » quench. We find that although electronic carriers are immediately delocalized, the crystal symmetry remains initially frozen—as witnessed by time-delayed suppression of zone-folded Ni–O bending modes acting as a fingerprint of lattice symmetry. Longitudinal and transverse vibrations react with different speeds, indicating a strong directionality and an important role of polar interactions. As a result, the hidden complexity of electronic and structural coupling during stripe melting and formation, captured here within a single terahertz spectrum, opens new paths to understanding symmetry-breaking dynamics in solids.« less

Ultrafast dynamics of vibrational symmetry breaking in a charge-ordered nickelate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coslovich, Giacomo; Kemper, Alexander F.; Behl, Sascha

The ability to probe symmetry-breaking transitions on their natural time scales is one of the key challenges in nonequilibrium physics. Stripe ordering represents an intriguing type of broken symmetry, where complex interactions result in atomic-scale lines of charge and spin density. Although phonon anomalies and periodic distortions attest the importance of electron-phonon coupling in the formation of stripe phases, a direct time-domain view of vibrational symmetry breaking is lacking. We report experiments that track the transient multi-terahertz response of the model stripe compound La 1.75Sr 0.25NiO 4, yielding novel insight into its electronic and structural dynamics following an ultrafast opticalmore » quench. We find that although electronic carriers are immediately delocalized, the crystal symmetry remains initially frozen—as witnessed by time-delayed suppression of zone-folded Ni–O bending modes acting as a fingerprint of lattice symmetry. Longitudinal and transverse vibrations react with different speeds, indicating a strong directionality and an important role of polar interactions. As a result, the hidden complexity of electronic and structural coupling during stripe melting and formation, captured here within a single terahertz spectrum, opens new paths to understanding symmetry-breaking dynamics in solids.« less

X-Ray Fluctuation Power Spectral Densities of Seyfert 1 Galaxies

NASA Technical Reports Server (NTRS)

Markowitz, A.; Edelson, R.; Vaughan, S.; Uttley, P.; George, I. M.; Griffiths, R. E.; Kaspi, S.; Lawrence, A.; McHandy, I.; Nandra, K.

2003-01-01

By combining complementary monitoring observations spanning long, medium and short time scales, we have constructed power spectral densities (PSDs) of six Seyfert 1 galaxies. These PSDs span approx. greater than 4 orders of magnitude in temporal frequency, sampling variations on time scales ranging from tens of minutes to over a year. In at least four cases, the PSD shows a "break," a significant departure from a power law, typically on time scales of order a few days. This is similar to the behavior of Galactic X-ray binaries (XRBs), lower mass compact systems with breaks on time scales of seconds. NGC 3783 shows tentative evidence for a doubly-broken power law, a feature that until now has only been seen in the (much better-defined) PSDs of low-state XRBs. It is also interesting that (when one previously-observed object is added to make a small sample of seven), an apparently significant correlation is seen between the break time scale T and the putative black hole mass M(sub BH), while none is seen between break time scale and luminosity. The data are consistent with the linear relation T = M(sub BH) /10(exp 6.5) solar mass; extrapolation over 6-7 orders of magnitude is in reasonable agreement with XRBs. All of this strengthens the case for a physical similarity between Seyfert 1s and XRBs.

Parity-time symmetry breaking in magnetic systems

DOE PAGES

Galda, Alexey; Vinokur, Valerii M.

2016-07-14

The understanding of out-of-equilibrium physics, especially dynamic instabilities and dynamic phase transitions, is one of the major challenges of contemporary science, spanning the broadest wealth of research areas that range from quantum optics to living organisms. By focusing on nonequilibrium dynamics of an open dissipative spin system, we introduce a non-Hermitian Hamiltonian approach, in which non-Hermiticity reflects dissipation and deviation from equilibrium. The imaginary part of the proposed spin Hamiltonian describes the effects of Gilbert damping and applied Slonczewski spin-transfer torque. In the classical limit, our approach reproduces Landau-Lifshitz-Gilbert-Slonczewski dynamics of a large macrospin. Here, we reveal the spin-transfer torque-drivenmore » parity-time symmetry-breaking phase transition corresponding to a transition from precessional to exponentially damped spin dynamics. Micromagnetic simulations for nanoscale ferromagnetic disks demonstrate the predicted effect. These findings can pave the way to a general quantitative description of out-of-equilibrium phase transitions driven by spontaneous parity-time symmetry breaking.« less

Low Sleeping Time, High TV Viewing Time, and Physical Inactivity in School Are Risk Factors for Obesity in Pre-Adolescent Thai Children.

PubMed

Thasanasuwan, Wiyada; Srichan, Weerachat; Kijboonchoo, Kallaya; Yamborisut, Uruwan; Wimonpeerapattana, Wanphen; Rojroongwasinkul, Nipa; Khouw, Ilse Tan; Deurenberg, Pual

2016-03-01

Explore the association between physically active behavior and obesity in 7- to 12-years-old Thai children. As part of SEANUTS Thailand, information on anthropometry, physical activity, and sociodemographic variables were collected in 7- to 12-years-old urban and rural Thai children. Multi-stage sampling technique was used and 1,345 children (32% urban, and 50.3% boys) participated in the study. Anthropometric measurements included weight, height, and BMI-for-age Z-scores (BAZ) using World Health Organization Growth Reference. Obesity was defined as BAZ > 2SD. Physical activity was assessed using a validated physical activity questionnaire (PAQ). The PAQ provided an activity score, activity time in school, sleeping hours, and TV watching time as categorical variable, low, moderate, and high. Chi-square by likelihood ratio test and logistic regression were used to compare obese and non-obese groups. The overall prevalence of overweight and obesity was 10.2 and 10.8% respectively, whereas 8.2% was classified as thin. Maternal education and religion did not differ between obese and non-obese children. However, obese children's family income was higher. After controlling for family income, maternal education, and religion, obese children were significantly less active during break times in school, slept less, and watched more TV than non-obese. However, there was no difference in the activity score of obese and non-obese children. The study showed that physical activity during break time in school, sleep duration, and hours of TV viewing were associated with obesity in pre-adolescent Thai children. It is important to note that activity score was not associated with obesity. One of the most important benefits to be physically active in childhood is the potential to maintain this behavior into adulthood. Therefore, programs that encourage healthy behaviors and address these modifiable risk factors should be incorporated in the school curriculum.

Time-Reversal Symmetry Breaking and Consequent Physical Responses Induced by All-In-All-Out Type Magnetic Order on the Pyrochlore Lattice

NASA Astrophysics Data System (ADS)

Arima, Taka-Hisa

2014-03-01

Pyrochlore-type 5d transition-metal oxide compounds Cd2Os2O7 and R2Ir2O7 (R =rare earth) undergo a metal-insulator transition accompanied by a magnetic transition. Recently, the magnetic structures of Cd2Os2O7 and Eu2Ir2O7 were investigated by means of resonant x-ray magnetic scattering. The x-ray data indicated the all-in/all-out type magnetic order. The all-in/all-out order breaks the time-reversal symmetry, while the spontaneous magnetization is essentially absent. The magnetic order can be viewed as ferroic magnetic octupolar order. The magnetic order is expected to provide several unique physical properties like quadratic magnetization. linear magneto-capacitance, linear magneto-resistance, linear magneto-mechanical coupling and so on. The symmetry breaking results in two non-equivalent domains, ``all-in/all-out'' and ``all-out/all-in.'' Interestingly, some theoretical works predict that a peculiar metallic state would appear on the domain wall. The observation and control of the domain distribution are essential for studying verious exotic physical responses. We have developed an x-ray technique for domain imaging and started studying the effects of external stimuli on the domain distribution. This work was performed in collaboration with S. Tardif, S. Takeshita, H. Ohsumi, D. Uematsu, H. Sagayama, J. J. Ishikawa, S. Nakatsuji, J. Yamaura, and Z. Hiroi.

Fermion systems in discrete space-time

NASA Astrophysics Data System (ADS)

Finster, Felix

2007-05-01

Fermion systems in discrete space-time are introduced as a model for physics on the Planck scale. We set up a variational principle which describes a non-local interaction of all fermions. This variational principle is symmetric under permutations of the discrete space-time points. We explain how for minimizers of the variational principle, the fermions spontaneously break this permutation symmetry and induce on space-time a discrete causal structure.

GRB 091127: The Cooling Break Race on Magnetic Fuel

NASA Technical Reports Server (NTRS)

Filgas, R.; Greiner, J.; Schady, P.; Kruhler, T.; Updike, A. C.; Klose, S.; Nardini, M.; Kann, D. A.; Rossi, A.; Sudilovsky, V.;

Weak ergodicity breaking, irreproducibility, and ageing in anomalous diffusion processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metzler, Ralf

2014-01-14

Single particle traces are standardly evaluated in terms of time averages of the second moment of the position time series r(t). For ergodic processes, one can interpret such results in terms of the known theories for the corresponding ensemble averaged quantities. In anomalous diffusion processes, that are widely observed in nature over many orders of magnitude, the equivalence between (long) time and ensemble averages may be broken (weak ergodicity breaking), and these time averages may no longer be interpreted in terms of ensemble theories. Here we detail some recent results on weakly non-ergodic systems with respect to the time averagedmore » mean squared displacement, the inherent irreproducibility of individual measurements, and methods to determine the exact underlying stochastic process. We also address the phenomenon of ageing, the dependence of physical observables on the time span between initial preparation of the system and the start of the measurement.« less

Children with Physical Disabilities at School and Home: Physical Activity and Contextual Characteristics.

PubMed

Li, Ru; Sit, Cindy Hui-Ping; Yu, Jane Jie; Sum, Raymond Kim-Wai; Wong, Stephen Heung-Sang; Cheng, Kenneth Chik-Chi; McKenzie, Thomas L

2017-06-25

The purpose of this study was to assess the physical activity (PA) of children with physical disabilities (PD) in school and home settings and to simultaneously examine selected contextual characteristics in relation to PA in those settings. Children with PD (N = 35; Mean age = 15.67 ± 4.30 years; 26 boys) were systematically observed using BEACHES (Behaviors of Eating and Activity for Children's Health: Evaluation System) at school (before school, recess, lunch break, after class) and at home (before dinner) during four normal school days. The children spent most of their time in all five settings being physically inactive, but had slightly more PA during recess and lunch break periods. Hierarchical multiple regression revealed that selected contextual characteristics explained 18.9-56.0% ( p < 0.01) of the variance predicting moderate-to-vigorous physical activity (MVPA) after controlling for demographic variables. Prompts to be active were positively associated with MVPA at school and the presence of fathers and fathers being motivators at home. This study highlights how little PA that children with PD receive and identifies the importance of the provision of prompts for PA at both school and home with this special population.

Predictors of physical activity and sedentary behaviours among 11-16 year olds: Multilevel analysis of the 2013 Health Behaviour in School-aged Children (HBSC) study in Wales.

PubMed

Morgan, Kelly; Hallingberg, Britt; Littlecott, Hannah; Murphy, Simon; Fletcher, Adam; Roberts, Chris; Moore, Graham

2016-07-15

The present study investigated associations between individual- and school-level predictors and young people's self-reported physical activity (total activity and moderate-to-vigorous activity) and sedentary behaviours. Individual-level data provided by the 2013/14 cross-sectional survey 'Health Behaviour in School-aged Children (HBSC) study in Wales' were linked to school-level data within the 'HBSC School Environment Questionnaire'. The final sample comprised 7,376 young people aged 11-16 years across 67 schools. Multilevel modelling was used to examine predictors of total physical activity, moderate-to-vigorous physical activity (MVPA) and sedentary behaviours (screen-based behaviours). Taking more physical activity (less than 5 days vs. 5 or more days per week), engaging in higher levels of MVPA (less than 4 hours vs. 4 or more hours per week) and reporting 2 or less hours of sedentary time were predicted by several individual level variables. Active travel to school positively predicted high levels of physical activity, however, gender stratified models revealed active travel as a predictor amongst girls only (OR:1.25 (95 % CI:1.05 - 1.49)). No school-level factors were shown to predict physical activity levels, however, a lower school socio-economic status was associated with a higher level of MVPA (OR:1.02 (95 % CI:1.01 - 1.03)) and a lower risk of sedentary behaviour (OR:0.97 (95 % CI:0.96 - 0.99)). A shorter lunch break (OR:1.33 (95 % CI:1.11 - 1.49)) and greater provision of facilities (OR:1.02 (95 % CI:1.00 - 1.05)) were associated with increased sedentary activity. Gender stratified models revealed that PE lesson duration (OR:1.18 (95 % CI:1.01 - 1.37)) and the provision of sports facilities (OR:1.03 (95 % CI:1.00 - 1.06)) were predictors of boy's sedentary behaviours only. Shorter lunch breaks were associated with increased sedentary time. Therefore, while further research is needed to better understand the causal nature of this association, extending lunch breaks could have a positive impact on sedentary behaviour through the provision of more time for physical activity. The findings also suggest that active travel could offer a mechanism for increasing physical activity levels particularly amongst girls. Particularly, the design and evaluation of interventions to promote physical activity during school hours should employ a comprehensive approach, including a focus on school policies and behaviours both in and out of school hours.

Improving Cardiometabolic Health with Diet, Physical Activity, and Breaking Up Sitting: What about Sleep?

PubMed Central

Vincent, Grace E.; Jay, Sarah M.; Sargent, Charli; Vandelanotte, Corneel; Ridgers, Nicola D.; Ferguson, Sally A.

2017-01-01

Cardiometabolic disease poses a serious health and economic burden worldwide and its prevalence is predicted to increase. Prolonged sitting, lack of physical activity, poor diet, and short sleep duration are ubiquitous behaviors in modern society, and all are independent risk factors in the development of cardiometabolic disease. Existing evidence demonstrates that breaking up prolonged periods of sitting is beneficial for cardiometabolic health, however, studies have not controlled for prior sleep duration. This article examines how prolonged sitting and short sleep duration independently contribute to cardiometabolic risk, and how breaking up sitting and obtaining adequate sleep may reduce this risk. We suggest that as prolonged sitting and short sleep duration influence the same cardiometabolic parameters, there is potential for short sleep to attenuate the positive impact of breaking up prolonged sitting with physical activity. Likewise, breaking up prolonged sitting and obtaining adequate sleep together could improve predictors of cardiometabolic disease, i.e., the combined effect may be stronger than either alone. To explore these perspectives, we propose a research agenda to investigate the relationship between breaking up prolonged sitting with physical activity and short sleep duration. This will provide an evidence-base for informing the design of interventions to reduce the burden of cardiometabolic disease on communities worldwide. PMID:29167645

Spontaneous Symmetry Breaking in Nonrelativistic Systems

NASA Astrophysics Data System (ADS)

Watanabe, Haruki

The subject of condensed matter physics is very rich --- there are an infinite number of parameters producing a diversity of exciting phenomena. As a theorist, my goal is to distill general principles out of this complexity --- to construct theories that can coherently explain many known examples altogether. This thesis is composed of several attempts to develop such theories in topics related to spontaneously symmetry breaking. A remarkable feature of many-body interacting systems is that although they are described by equations respecting various symmetries, they may spontaneously organize into a state that explicitly breaks symmetries. Examples are numerous: various types of crystalline and magnetic orders, Bose-Einstein condensates of cold atoms, superfluids of liquid helium, chiral symmetry in QCD, neutron stars, and cosmic inflation. These systems with spontaneously broken continuous symmetries have gapless excitations, so called Nambu-Goldstone bosons (NGBs). Although the properties of NGBs are well understood in Lorentz-invariant systems, surprisingly, some basic properties of NGBs such as their number and dispersion in nonrelativistic systems have not been discussed from a general perspective. In the first part of this thesis, we solve this issue by developing and analyzing an effective Lagrangian that coherently captures the low-energy, long-distance physics of many different symmetry-breaking states all at once. Next, we examine whether these NGBs originating from spontaneous symmetry breaking remain to be well-defined excitations inside a metal, where low-energy electrons near Fermi surface can collide with them. Our result is a one equation criterion that specifies whether the interactions between electrons and NGBs can be ignored, or whether it completely changes their character. In the latter case, unusual phases of matter such as non-Fermi liquids may arise; in that case, NGBs are overdamped and cannot form particle-like excitations in spite of the assumed symmetry breaking. In the last part of this thesis, we investigate the possibility of spontaneously breaking of Hamiltonian itself. The homogeneity of time is one of the most fundamental symmetries of nature, underlying the conservation of the energy. The question is whether this symmetry can be spontaneously broken, as suggested recently by Wilczek, in analogy with ordinary crystals. Contrary to his proposal that attracted a significant attention and stimulated many further studies, we prove a no-go theorem that rules out spontaneously breaking of time translation, in the ground state or in the canonical ensemble of a general Hamiltonian.

Occupational Sitting and Physical Activity Among University Employees.

PubMed

Fountaine, Charles J; Piacentini, Meredith; Liguori, Gary A

The prevalence of overweight and obese in the U.S. has been thoroughly documented. With the advent of inactivity physiology research and the subsequent interest in sedentary behavior, the work environment has come under closer scrutiny as a potential opportunity to reverse inactivity. Therefore, the purpose of this study was to determine the sitting and physical activity (PA) habits among different classifications of university employees. University employees (n=625) completed an online survey based on the Occupational Sitting and Physical Activity Questionnaire (OSPAQ). Participants were instructed to describe time spent sitting, standing, walking, and in heavy physical labor during the last seven days, along with the number of breaks from sitting taken per hour. To establish habitual patterns of PA outside of work, employees recalled their participation in structured PA in the past seven days. Prior to data analysis, employees were categorized as Administration, Faculty, Staff, or Facilities Management. Statistically significant differences were found among employee classifications for min sit/d, p<.001; min stand/d, p<.001; min walk/d, p<.001; and min heavy labor/d, p<.001. No significant differences were found for breaks/h from sitting, p=.259 or participation in structured PA, p=. 33. With the exception of facilities management workers, university employees spent 75% of their workday seated. In conjunction with low levels of leisure time PA, university employees appear to be prime candidates for workplace interventions to reduce physical inactivity.

Quantum anomalous Hall effect in time-reversal-symmetry breaking topological insulators

NASA Astrophysics Data System (ADS)

Chang, Cui-Zu; Li, Mingda

2016-03-01

The quantum anomalous Hall effect (QAHE), the last member of Hall family, was predicted to exhibit quantized Hall conductivity {σyx}=\\frac{{{e}2}}{h} without any external magnetic field. The QAHE shares a similar physical phenomenon with the integer quantum Hall effect (QHE), whereas its physical origin relies on the intrinsic topological inverted band structure and ferromagnetism. Since the QAHE does not require external energy input in the form of magnetic field, it is believed that this effect has unique potential for applications in future electronic devices with low-power consumption. More recently, the QAHE has been experimentally observed in thin films of the time-reversal symmetry breaking ferromagnetic (FM) topological insulators (TI), Cr- and V- doped (Bi,Sb)2Te3. In this topical review, we review the history of TI based QAHE, the route to the experimental observation of the QAHE in the above two systems, the current status of the research of the QAHE, and finally the prospects for future studies.

MOTOR SKILLS AND NUTRITIONAL STATUS OUTCOMES FROM A PHYSICAL ACTIVITY INTERVENTION IN SHORT BREAKS ON PRESCHOOL CHILDREN CONDUCTED BY THEIR EDUCATORS: A PILOT STUDY.

PubMed

Monsalves-Alvarez, Matias; Castro-Sepulveda, Mauricio; Zapata-Lamana, Rafael; Rosales-Soto, Giovanni; Salazar, Gabriela

2015-10-01

childhood obesity is a worldwide health concern. For this issue different intervention have being planned to increase physical activity patterns and reduce the excess of weight in children with limited or no success. the aim of this study is to evaluate the results of a pilot intervention consisting in three 15-minute breaks conducted by educators and supervised by physical education teachers on motor skills and nutritional status in preschool children. sample was 70 preschool children (32 boys and 38 girls), age 4 ± 0,6 years. The physical activity classes were performed three times a week, 45 minutes daily, distributed in three 15 minutes breaks. The circuits were planned to have; jumps, sprints, carrying medicinal balls, gallops and crawling. Motor skill tests that were performed Standing long jump (SLJ) and Twelve meter run. with the intervention no significant differences in nutritional status where found on mean Z score (boys p = 0.49, girls p = 0.77). An increment on weight and height was fount after the intervention (p < 0.0001). Regarding the 12 meter run test, we found significant changes after the intervention when we normalize by weight in boys (p = 0.002) and girls (p < 0.0001). Our results have shown than boys significantly increased their SLJ and SLJ normalized by weight (p < 0.0001); a similar result was found in girls after the intervention (p < 0.0001) suggesting the increment of power independent of weight gain. in conclusion, this pilot study found that an intervention with more intense activities in small breaks (15 minutes), and guided by the educators could improve essential motor skills (running and jumping) in preschool children of a semi-rural sector independent of nutritional status. This gaining in motor skills is the first step to increase physical activity levels in preschool children. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Promoting Teacher Adoption of Physical Activity Breaks in the Classroom: Findings of the Central Texas Catch Middle School Project

ERIC Educational Resources Information Center

Delk, Joanne; Springer, Andrew E.; Kelder, Steven H.; Grayless, Megan

2014-01-01

Background: Research suggests that physical activity breaks (ABs) during class increase students' physical activity levels and provide an academic benefit. This study evaluates a 3-year intervention aimed at encouraging teacher AB use. Methods: Thirty central Texas middle schools were assigned to 1 of 3 conditions: training-only…

Instantaneous Velocity Using Photogate Timers

ERIC Educational Resources Information Center

Wolbeck, John

2010-01-01

Photogate timers are commonly used in physics laboratories to determine the velocity of a passing object. In this application a card attached to a moving object breaks the beam of the photogate timer providing the time for the card to pass. The length L of the passing card can then be divided by this time to yield the average velocity (or speed)…

NIMROD resistive magnetohydrodynamic simulations of spheromak physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooper, E. B.; Cohen, B. I.; McLean, H. S.

The physics of spheromak plasmas is addressed by time-dependent, three-dimensional, resistive magnetohydrodynamic simulations with the NIMROD code [C. R. Sovinec et al., J. Comput. Phys. 195, 355 (2004)]. Included in some detail are the formation of a spheromak driven electrostatically by a coaxial plasma gun with a flux-conserver geometry and power systems that accurately model the sustained spheromak physics experiment [R. D. Wood et al., Nucl. Fusion 45, 1582 (2005)]. The controlled decay of the spheromak plasma over several milliseconds is also modeled as the programmable current and voltage relax, resulting in simulations of entire experimental pulses. Reconnection phenomena andmore » the effects of current profile evolution on the growth of symmetry-breaking toroidal modes are diagnosed; these in turn affect the quality of magnetic surfaces and the energy confinement. The sensitivity of the simulation results addresses variations in both physical and numerical parameters, including spatial resolution. There are significant points of agreement between the simulations and the observed experimental behavior, e.g., in the evolution of the magnetics and the sensitivity of the energy confinement to the presence of symmetry-breaking magnetic fluctuations.« less

NIMROD Resistive Magnetohydrodynamic Simulations of Spheromak Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooper, E B; Cohen, B I; McLean, H S

The physics of spheromak plasmas is addressed by time-dependent, three-dimensional, resistive magneto-hydrodynamic simulations with the NIMROD code. Included in some detail are the formation of a spheromak driven electrostatically by a coaxial plasma gun with a flux-conserver geometry and power systems that accurately model the Sustained Spheromak Physics Experiment (SSPX) (R. D. Wood, et al., Nucl. Fusion 45, 1582 (2005)). The controlled decay of the spheromak plasma over several milliseconds is also modeled as the programmable current and voltage relax, resulting in simulations of entire experimental pulses. Reconnection phenomena and the effects of current profile evolution on the growth ofmore » symmetry-breaking toroidal modes are diagnosed; these in turn affect the quality of magnetic surfaces and the energy confinement. The sensitivity of the simulation results address variations in both physical and numerical parameters, including spatial resolution. There are significant points of agreement between the simulations and the observed experimental behavior, e.g., in the evolution of the magnetics and the sensitivity of the energy confinement to the presence of symmetry-breaking magnetic fluctuations.« less

School related factors and 1yr change in physical activity amongst 9-11 year old English schoolchildren.

PubMed

Mantjes, Joyce A; Jones, Andrew P; Corder, Kirsten; Jones, Natalia R; Harrison, Flo; Griffin, Simon J; van Sluijs, Esther M F

2012-12-31

Activity levels are known to decline with age and there is growing evidence of associations between the school environment and physical activity. In this study we investigated how objectively measured one-year changes in physical activity may be associated with school-related factors in 9- to 10-year-old British children. Data were analysed from 839 children attending 89 schools in the SPEEDY (Sport, Physical Activity, and Eating behaviours: Environmental Determinants in Young People) study. Outcomes variables were one year changes in objectively measured sedentary, moderate, and vigorous physical activity, with baseline measures taken when the children were 9-10 years old. School characteristics hypothesised to be associated with change in physical activity were identified from questionnaires, grounds audits, and computer mapping. Associations were examined using simple and multivariable multilevel regression models for both school (9 am - 3 pm) and travel (8-9 am and 3-4 pm) time. Significant associations during school time included the length of the morning break which was found to be supportive of moderate (β coefficient: 0.68 [p: 0.003]) and vigorous (β coefficient: 0.52 [p: 0.002]) activities and helps to prevent adverse changes in sedentary time (β coefficient: -2.52 [p: 0.001]). During travel time, positive associations were found between the presence of safe places to cross roads around the school and changes in moderate (β coefficient: 0.83 [p:0.022]) and vigorous (β coefficient: 0.56 [p:0.001]) activity, as well as sedentary time (β coefficient: -1.61 [p:0.005]). This study suggests that having longer morning school breaks and providing road safety features such as cycling infrastructure, a crossing guard, and safe places for children to cross the road may have a role to play in supporting the maintenance of moderate and vigorous activity behaviours, and preventing the development of sedentary behaviours in children.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tannenbaum, Michael J.

The search for the left-handed W± bosons, the proposed quanta of the weak interaction, and the Higgs boson, which spontaneously breaks the symmetry of unification of electromagnetic and weak interactions, has driven elementary-particle physics research from the time that I entered college to the present and has led to many unexpected and exciting discoveries which revolutionized our view of subnuclear physics over that period. In this article I describe how these searches and discoveries have intertwined with my own career.

Joint trajectories for social and physical aggression as predictors of adolescent maladjustment: internalizing symptoms, rule-breaking behaviors, and borderline and narcissistic personality features.

PubMed

Underwood, Marion K; Beron, Kurt J; Rosen, Lisa H

2011-05-01

This investigation examined the relation between developmental trajectories jointly estimated for social and physical aggression and adjustment problems at age 14. Teachers provided ratings of children's social and physical aggression in Grades 3, 4, 5, 6, and 7 for a sample of 255 children (131 girls, 21% African American, 52% European American, 21% Mexican American). Participants, parents, and teachers completed measures of the adolescent's adjustment to assess internalizing symptoms, rule-breaking behaviors, and borderline and narcissistic personality features. Results showed that membership in a high and rising trajectory group predicted rule-breaking behaviors and borderline personality features. Membership in a high desister group predicted internalizing symptoms, rule-breaking behaviors, and borderline and narcissistic personality features. The findings suggest that although low levels of social and physical aggression may not bode poorly for adjustment, individuals engaging in high levels of social and physical aggression in middle childhood may be at greatest risk for adolescent psychopathology, whether they increase or desist in their aggression through early adolescence.

Joint trajectories for social and physical aggression as predictors of adolescent maladjustment: Internalizing symptoms, rule-breaking behaviors, and borderline and narcissistic personality features

PubMed Central

UNDERWOOD, MARION K.; BERON, KURT J.; ROSEN, LISA H.

2011-01-01

This investigation examined the relation between developmental trajectories jointly estimated for social and physical aggression and adjustment problems at age 14. Teachers provided ratings of children's social and physical aggression in Grades 3, 4, 5, 6, and 7 for a sample of 255 children (131 girls, 21% African American, 52% European American, 21% Mexican American). Participants, parents, and teachers completed measures of the adolescent's adjustment to assess internalizing symptoms, rule-breaking behaviors, and borderline and narcissistic personality features. Results showed that membership in a high and rising trajectory group predicted rule-breaking behaviors and borderline personality features. Membership in a high desister group predicted internalizing symptoms, rule-breaking behaviors, and borderline and narcissistic personality features. The findings suggest that although low levels of social and physical aggression may not bode poorly for adjustment, individuals engaging in high levels of social and physical aggression in middle childhood may be at greatest risk for adolescent psychopathology, whether they increase or desist in their aggression through early adolescence. PMID:21532919

The conceptualization of a Just-In-Time Adaptive Intervention (JITAI) for the reduction of sedentary behavior in older adults.

PubMed

Müller, Andre Matthias; Blandford, Ann; Yardley, Lucy

2017-01-01

Low physical activity and high sedentary behavior in older adults can be addressed with interventions that are delivered through modern technology. Just-In-Time Adaptive Interventions (JITAIs) are an emerging technology-driven behavior-change intervention type and capitalize on data that is collected via mobile sensing technology (e.g., smartphones) to trigger appropriate support in real-life. In this paper we integrated behavior change and aging theory and research as well as knowledge around older adult's technology use to conceptualize a JITAI targeting the reduction of sedentary behavior in older adults. The JITAIs ultimate goal is to encourage older adults to take regular activity breaks from prolonged sitting. As a proximal outcome, we suggest the number of daily activity breaks from sitting. Support provided to interrupt sitting time can be based on tailoring variables: (I) the current accumulated sitting time; (II) the location of the individual; (III) the time of the day; (IV) the frequency of daily support prompts; and (V) the response to previous support prompts. Data on these variables can be collected using sensors that are commonly inbuilt into smartphones (e.g., accelerometer, GPS). Support prompts might be best delivered via traditional text messages as older adults are usually familiar and comfortable with this function. The content of the prompts should encourage breaks from prolonged sitting by highlighting immediate benefits of sitting time interruptions. Additionally, light physical activities that could be done during the breaks should also be presented (e.g., walking into the kitchen to prepare a cup of tea). Although the conceptualized JITAI can be developed and implemented to test its efficacy, more work is required to identify ways to collect, aggregate, organize and immediately use dense data on the proposed and other potentially important tailoring variables. Machine learning and other computational modelling techniques commonly used by computer scientists and engineers appear promising. With this, to develop powerful JITAIs and to actualize the full potential of modern sensing technologies transdisciplinary approaches are required.

The conceptualization of a Just-In-Time Adaptive Intervention (JITAI) for the reduction of sedentary behavior in older adults

PubMed Central

Blandford, Ann; Yardley, Lucy

2017-01-01

Low physical activity and high sedentary behavior in older adults can be addressed with interventions that are delivered through modern technology. Just-In-Time Adaptive Interventions (JITAIs) are an emerging technology-driven behavior-change intervention type and capitalize on data that is collected via mobile sensing technology (e.g., smartphones) to trigger appropriate support in real-life. In this paper we integrated behavior change and aging theory and research as well as knowledge around older adult's technology use to conceptualize a JITAI targeting the reduction of sedentary behavior in older adults. The JITAIs ultimate goal is to encourage older adults to take regular activity breaks from prolonged sitting. As a proximal outcome, we suggest the number of daily activity breaks from sitting. Support provided to interrupt sitting time can be based on tailoring variables: (I) the current accumulated sitting time; (II) the location of the individual; (III) the time of the day; (IV) the frequency of daily support prompts; and (V) the response to previous support prompts. Data on these variables can be collected using sensors that are commonly inbuilt into smartphones (e.g., accelerometer, GPS). Support prompts might be best delivered via traditional text messages as older adults are usually familiar and comfortable with this function. The content of the prompts should encourage breaks from prolonged sitting by highlighting immediate benefits of sitting time interruptions. Additionally, light physical activities that could be done during the breaks should also be presented (e.g., walking into the kitchen to prepare a cup of tea). Although the conceptualized JITAI can be developed and implemented to test its efficacy, more work is required to identify ways to collect, aggregate, organize and immediately use dense data on the proposed and other potentially important tailoring variables. Machine learning and other computational modelling techniques commonly used by computer scientists and engineers appear promising. With this, to develop powerful JITAIs and to actualize the full potential of modern sensing technologies transdisciplinary approaches are required PMID:29184889

Oral Anatomy Laboratory Examinations in a Physical Therapy Program

ERIC Educational Resources Information Center

Fabrizio, Philip A.

2013-01-01

The process of creating and administering traditional tagged anatomy laboratory examinations is time consuming for instructors and limits laboratory access for students. Depending on class size and the number of class, sections, creating, administering, and breaking down a tagged laboratory examination may involve one to two eight-hour days.…

Time to Discover NFM

ERIC Educational Resources Information Center

Schaffer, Greg

2007-01-01

Managing resource usage and data delivery with virtualization devices is a staple of many of today's data infrastructures. By breaking the traditional direct physical access and inserting an abstraction layer, what one sees is what he/she gets, but the mechanics of delivery may be quite different. The reason for the increase in virtualization…

Amphiphilic nanoparticles suppress droplet break-up in a concentrated emulsion flowing through a narrow constriction

PubMed Central

Gai, Ya; Kim, Minkyu; Pan, Ming; Tang, Sindy K. Y.

2017-01-01

This paper describes the break-up behavior of a concentrated emulsion comprising drops stabilized by amphiphilic silica nanoparticles flowing in a tapered microchannel. Such geometry is often used in serial droplet interrogation and sorting processes in droplet microfluidics applications. When exposed to high viscous stresses, drops can undergo break-up and compromise their physical integrity. As these drops are used as micro-reactors, such compromise leads to a loss in the accuracy of droplet-based assays. Here, we show droplet break-up is suppressed by replacing the fluoro-surfactant similar to the one commonly used in current droplet microfluidics applications with amphiphilic nanoparticles as droplet stabilizer. We identify parameters that influence the break-up of these drops and demonstrate that break-up probability increases with increasing capillary number and confinement, decreasing nanoparticle size, and is insensitive to viscosity ratio within the range tested. Practically, our results reveal two key advantages of nanoparticles with direct applications to droplet microfluidics. First, replacing surfactants with nanoparticles suppresses break-up and increases the throughput of the serial interrogation process to 3 times higher than that in surfactant system under similar flow conditions. Second, the insensitivity of break-up to droplet viscosity makes it possible to process samples having different composition and viscosities without having to change the channel and droplet geometry in order to maintain the same degree of break-up and corresponding assay accuracy. PMID:28652887

Carbohydrates for Soccer: A Focus on Skilled Actions and Half-Time Practices

PubMed Central

Hills, Samuel P.; Russell, Mark

2017-01-01

Carbohydrate consumption is synonymous with soccer performance due to the established effects on endogenous energy store preservation, and physical capacity maintenance. For performance-enhancement purposes, exogenous energy consumption (in the form of drinks, bars, gels and snacks) is recommended on match-day; specifically, before and during match-play. Akin to the demands of soccer, limited opportunities exist to consume carbohydrates outside of scheduled breaks in competition, such as at half-time. The link between cognitive function and blood glucose availability suggests that carbohydrates may influence decision-making and technical proficiency (e.g., soccer skills). However, relatively few reviews have focused on technical, as opposed to physical, performance while also addressing the practicalities associated with carbohydrate consumption when limited in-play feeding opportunities exist. Transient physiological responses associated with reductions in activity prevalent in scheduled intra-match breaks (e.g., half-time) likely have important consequences for practitioners aiming to optimize match-day performance. Accordingly, this review evaluated novel developments in soccer literature regarding (1) the ergogenic properties of carbohydrates for skill performance; and (2) novel considerations concerning exogenous energy provision during half-time. Recommendations are made to modify half-time practices in an aim to enhance subsequent performance. Viable future research opportunities exist regarding a deeper insight into carbohydrate provision on match-day. PMID:29295583

Microphysics and dynamics of the gamma-ray burst 121024A

NASA Astrophysics Data System (ADS)

Varela, K.; van Eerten, H.; Greiner, J.; Schady, P.; Elliott, J.; Sudilovsky, V.; Krühler, T.; van der Horst, A. J.; Bolmer, J.; Knust, F.; Agurto, C.; Azagra, F.; Belloche, A.; Bertoldi, F.; De Breuck, C.; Delvaux, C.; Filgas, R.; Graham, J. F.; Kann, D. A.; Klose, S.; Menten, K. M.; Nicuesa Guelbenzu, A.; Rau, A.; Rossi, A.; Schmidl, S.; Schuller, F.; Schweyer, T.; Tanga, M.; Weiss, A.; Wiseman, P.; Wyrowski, F.

2016-05-01

Aims: The aim of the study is to constrain the physics of gamma-ray bursts (GRBs) by analysing the multi-wavelength afterglow data set of GRB 121024A that covers the full range from radio to X-rays. Methods: Using multi-epoch broad-band observations of the GRB 121024A afterglow, we measured the three characteristic break frequencies of the synchrotron spectrum. We used six epochs of combined XRT and GROND data to constrain the temporal slopes, the dust extinction, the X-ray absorption, and the spectral slope with high accuracy. Two more epochs of combined data from XRT, GROND, APEX, CARMA, and EVLA were used to set constraints on the break frequencies and therefore on the micro-physical and dynamical parameters. Results: The XRT and GROND light curves show a simultaneous and achromatic break at around 49 ks. As a result, the crossing of the synchrotron cooling break is no suitable explanation for the break in the light curve. The multi-wavelength data allow us to test two plausible scenarios explaining the break: a jet break, and the end of energy injection. The jet-break scenario requires a hard electron spectrum, a very low cooling break frequency, and a non-spreading jet. The energy injection avoids these problems, but requires ɛe > 1 (k = 2), spherical outflow, and ɛB < 10-9. Conclusions: In light of the extreme microphysical parameters required by the energy-injection model, we favour a jet-break scenario where νm < νsa to explain the observations. This scenario gives physically meaningful microphysical parameters, and it also naturally explains the reported detection of linear and circular polarisation.

Neural Entrainment in Drum Rhythms with Silent Breaks: Evidence from Steady-state Evoked and Event-related Potentials.

PubMed

Stupacher, Jan; Witte, Matthias; Hove, Michael J; Wood, Guilherme

2016-12-01

The fusion of rhythm, beat perception, and movement is often summarized under the term "entrainment" and becomes obvious when we effortlessly tap our feet or snap our fingers to the pulse of music. Entrainment to music involves a large network of brain structures, and neural oscillations at beat-related frequencies can help elucidate how this network is connected. Here, we used EEG to investigate steady-state evoked potentials (SSEPs) and event-related potentials (ERPs) during listening and tapping to drum clips with different rhythmic structures that were interrupted by silent breaks of 2-6 sec. This design allowed us to address the question of whether neural entrainment processes persist after the physical presence of musical rhythms and to link neural oscillations and event-related neural responses. During stimulus presentation, SSEPs were elicited in both tasks (listening and tapping). During silent breaks, SSEPs were only present in the tapping task. Notably, the amplitude of the N1 ERP component was more negative after longer silent breaks, and both N1 and SSEP results indicate that neural entrainment was increased when listening to drum rhythms compared with an isochronous metronome. Taken together, this suggests that neural entrainment to music is not solely driven by the physical input but involves endogenous timing processes. Our findings break ground for a tighter linkage between steady-state and transient evoked neural responses in rhythm processing. Beyond music perception, they further support the crucial role of entrained oscillatory activity in shaping sensory, motor, and cognitive processes in general.

GRB 091127: The cooling break race on magnetic fuel

NASA Astrophysics Data System (ADS)

Filgas, R.; Greiner, J.; Schady, P.; Krühler, T.; Updike, A. C.; Klose, S.; Nardini, M.; Kann, D. A.; Rossi, A.; Sudilovsky, V.; Afonso, P. M. J.; Clemens, C.; Elliott, J.; Nicuesa Guelbenzu, A.; Olivares E., F.; Rau, A.

2011-11-01

Aims: Using high-quality, broad-band afterglow data for GRB 091127, we investigate the validity of the synchrotron fireball model for gamma-ray bursts (GRBs), and infer physical parameters of the ultra-relativistic outflow. Methods: We used multi-wavelength (NIR to X-ray) follow-up observations obtained with GROND simultaneously in the g'r'i'z'JH filters and the XRT onboard the Swift satellite in the 0.3 to 10 keV energy range. The resulting afterglow light curve is of excellent accuracy with relative photometric errors as low as 1%, and the spectral energy distribution (SED) is well-sampled over 5 decades in energy. These data present one of the most comprehensive observing campaigns for a single GRB afterglow and allow us to test several proposed emission models and outflow characteristics in unprecedented detail. Results: Both the multi-color light curve and the broad-band SED of the afterglow of GRB 091127 show evidence of a cooling break moving from high to lower energies. The early light curve is well described by a broken power-law, where the initial decay in the optical/NIR wavelength range is considerably flatter than at X-rays. Detailed fitting of the time-resolved SED shows that the break is very smooth with a sharpness index of 2.2 ± 0.2, and evolves towards lower frequencies as a power-law with index - 1.23 ± 0.06. These are the first accurate and contemporaneous measurements of both the sharpness of the spectral break and its time evolution. Conclusions: The measured evolution of the cooling break (νc ∝ t~-1.2) is not consistent with the predictions of the standard model, wherein νc ∝ t~-0.5 is expected. A possible explanation for the observed behavior is a time dependence of the microphysical parameters, in particular the fraction of the total energy in the magnetic field ɛB. This conclusion provides further evidence that the standard fireball model is too simplistic, and time-dependent micro-physical parameters may be required to model the growing number of well-sampled afterglow light curves. Tables 3 and 4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A57

Energy expenditure and heart rate response to breaking up sedentary time with three different physical activity interventions.

PubMed

Carter, S E; Jones, M; Gladwell, V F

2015-05-01

Prolonged sedentary behaviour is associated with increased cardiovascular disease risk and decreased energy expenditure (EE). Workplace interventions breaking up sedentary time have increased EE but the cardiovascular responses are unknown. The practicalities of these interventions, such as required costs and workplace adaptations, are questioned. Calisthenics exercises overcome such limitations, but have not been assessed. The aim of this study was to assess the EE and heart rate (HR) response when breaking up sedentary time with a short bout of standing, walking or calisthenics. Twenty healthy participants (15 male) completed four 30 min conditions: a) 30 min sitting, or breaking up this period with two minutes of b) standing, c) treadmill walking (4 km·h(-1)) or d) a set of calisthenics exercises (including squats and lunges). HR and EE (indirect calorimetry) were assessed throughout. During the activity break, calisthenics caused the highest HR (90 ± 12 bpm) compared to all other conditions (Sit: 70 ± 12 bpm; Stand:72 ± 13 bpm; Walk:84 ± 10 bpm; p < 0.001) and EE was the highest with calisthenics (13 ± 5 kcal) compared to all conditions except walking (Sit:3 ± 1 kcal; Stand:5 ± 1 kcal; p < 0.001). The recovery following calisthenics had highest total EE (27 ± 7 kcal) compared to walking (23 ± 6 kcal) and standing (22 ± 6 kcal) and also the longest elevation of HR (p < 0.001). Calisthenics led to a greater total EE and HR response compared to standing or walking interventions. Calisthenics may be a time efficient method to break up sedentary time without individuals leaving their work environment. Hence calisthenics could be utilised to disrupt workplace sedentary time and improve cardiovascular health and assist in weight management. Copyright © 2015 Elsevier B.V. All rights reserved.

The Impact of Classroom Physical Activity Breaks on Middle School Students' Health-Related Fitness: An Xbox One Kinetic Delivered 4-Week Randomized Controlled Trial

ERIC Educational Resources Information Center

Yli-Piipari, S.; Layne, T.; McCollins, T.; Knox, T.

2016-01-01

The aim of the study was to examine the effect of a 4-week classroom physical activity break intervention on middle school students' health-related physical fitness. The study was a randomized controlled trial with students assigned to the experiment and control conditions. A convenience sample comprised 94 adolescents (experiment group n = 52;…

Participatory Workplace Interventions Can Reduce Sedentary Time for Office Workers—A Randomised Controlled Trial

PubMed Central

Parry, Sharon; Straker, Leon; Gilson, Nicholas D.; Smith, Anne J.

2013-01-01

Background Occupational sedentary behaviour is an important contributor to overall sedentary risk. There is limited evidence for effective workplace interventions to reduce occupational sedentary time and increase light activity during work hours. The purpose of the study was to determine if participatory workplace interventions could reduce total sedentary time, sustained sedentary time (bouts >30 minutes), increase the frequency of breaks in sedentary time and promote light intensity activity and moderate/vigorous activity (MVPA) during work hours. Methods A randomised controlled trial (ANZCTR number: ACTN12612000743864) was conducted using clerical, call centre and data processing workers (n = 62, aged 25–59 years) in 3 large government organisations in Perth, Australia. Three groups developed interventions with a participatory approach: ‘Active office’ (n = 19), ‘Active Workstation’ and promotion of incidental office activity; ‘Traditional physical activity’ (n = 14), pedometer challenge to increase activity between productive work time and ‘Office ergonomics’ (n = 29), computer workstation design and breaking up computer tasks. Accelerometer (ActiGraph GT3X, 7 days) determined sedentary time, sustained sedentary time, breaks in sedentary time, light intensity activity and MVPA on work days and during work hours were measured before and following a 12 week intervention period. Results For all participants there was a significant reduction in sedentary time on work days (−1.6%, p = 0.006) and during work hours (−1.7%, p = 0.014) and a significant increase in number of breaks/sedentary hour on work days (0.64, p = 0.005) and during work hours (0.72, p = 0.015); there was a concurrent significant increase in light activity during work hours (1.5%, p = 0.012) and MVPA on work days (0.6%, p = 0.012). Conclusions This study explored novel ways to modify work practices to reduce occupational sedentary behaviour. Participatory workplace interventions can reduce sedentary time, increase the frequency of breaks and improve light activity and MVPA of office workers by using a variety of interventions. Trial Registration Australian New Zealand Clinical Trials Registry ACTN12612000743864. PMID:24265734

Spontaneous Symmetry Breaking in Supernova Neutrinos

NASA Astrophysics Data System (ADS)

Raffelt, Georg G.

2015-08-01

Some recent developments in supernova neutrino physics are introduced where spontaneous symmetry breaking is a common theme. The physics of self-induced flavor conversion has acquired a new complication in that a new class of instabilities breaks axial symmetry of a neutrino stream, the multi-azimuth angle (MAA) instability. A completely different new phenomenon, discovered in the first realistic three-dimensional (3D) simulations, is the Lepton-Emission Self-sustained Asymmetry (LESA) during the accretion phase. Here, a neutrino-hydrodynamical instability breaks global spherical symmetry in that the lepton-number flux (νe minus ν‾e) develops a stable dipole pattern such that the lepton flux is almost exclusively emitted in one hemisphere.

A unified spectral,parameterization for wave breaking: from the deep ocean to the surf zone

NASA Astrophysics Data System (ADS)

Filipot, J.

2010-12-01

A new wave-breaking dissipation parameterization designed for spectral wave models is presented. It combines wave breaking basic physical quantities, namely, the breaking probability and the dissipation rate per unit area. The energy lost by waves is fi[|#12#|]rst calculated in the physical space before being distributed over the relevant spectral components. This parameterization allows a seamless numerical model from the deep ocean into the surf zone. This transition from deep to shallow water is made possible by a dissipation rate per unit area of breaking waves that varies with the wave height, wavelength and water depth.The parameterization is further tested in the WAVEWATCH III TM code, from the global ocean to the beach scale. Model errors are smaller than with most specialized deep or shallow water parameterizations.

Nuclear Time Delay Effects on K-Vacancy Production in Deep-Inelastic U+U Collisions

NASA Astrophysics Data System (ADS)

Molitoris, John David

1987-09-01

Atomic K-vacancy production in 7.5-MeV/u U+U collisons has been studied for small-impact-parameter (b) elastic scattering and for deep-inelastic nuclear reactions, by measuring coincidences between U x-rays and scattered U particles. The K-vacancy production probability (P(,K)(b)) in elastic U+U collisions was measured as a function of b and it is shown that P(,K) follows a scaling law from b = 10 to 85 fm. Below 10 fm, P(,K)(b) increases sharply from 0.91 (+OR-) 0.08 at 11.6 fm to a maximum of 1.8 (+OR -) 0.18 vacancies per collison at 7 fm. This behavior at small b could be due to rotational coupling of the 2p(,3/2)(pi), 2p(,3/2)(sigma) (--->) 2p(,1/2)(sigma) molecular orbitals, but present theoretical calculations do not reflect this. Since internal conversion is a major background in these measurements, it was necessary to observe how the internal conversion changes in elastic collisions as b (--->) 0, so that the internal conversion for atomic collisons accompanied by nuclear reactions could be understood. Nuclear-reaction effects of P(,K)(b (DBLTURN) 0) were studied as a function of the total kinetic energy loss (TKEL) of the nuclear interaction for 2-body break -up (U + U (--->) U' + U'') and 3-body break-up (U + U ( --->) U' + 2ff). In 4-body break-up (U + U (--->) 2ff' + 2ff''), P(,K) was measured over all TKEL. In 2-body break-up a 78% reduction of P(,K) is observed between TKEL = 0 and 275 MeV. This trend matches a theoretical decrease in P(,K)(T(,D)), where T(,D) in the nuclear interaction time or delay time. A parametric relation between TKEL and T(,D) can be formed between the theoretical calculation and the experimental result. A delay time of (0.52 (+OR -) 0.17) x 10('-21) sec at TKEL = 100 MeV is deter- mined. There is overall agreement between this atomic physics result and nuclear diffusion model calculations. The measured P(,K)(TKEL) for 3-body break-up is nearly identical to that of 2-body break-up. This indicates that there is a large compo- nent of fissioning nuclei ((TURN)50%) whose fission time (T(,f)) can not be much smaller than the U K-vacancy decay time (T(,K)(U) (DBLTURN) 10('-18) sec). The overall P(,K)('3-body) results and a study of distinct spatial orientations of the fission fragments in relation to the surviving U-like partner show a reduction in P(,K)('3-body) for TKEL >(, )175 MeV. This could imply that T(,f) (LESSTHEQ) 10('-18) sec for TKEL >(, )175 MeV. Measurement of the net U K x-ray yield over all TKEL in 4-body break-up reveals that P(,K)('4-body) = 0.36 (+OR-) 0.08. When compared to similar net probabilities for 2- and 3-body break-up, this indicates that about 50% of the U-like reaction partners which ultimately fission live at least 10('-18) sec. This result is in overall agreement with the 3-body results, but exceeds usual nuclear physics estimates of T(,f) (TURN) 10('-20) sec. However, crystal blocking techniques have observed long lived fission components (T(,f) (GREATERTHEQ) 10('-18) sec) in some nuclear reactions.

Physical Activity Breaks and Facilities in US Secondary Schools

ERIC Educational Resources Information Center

Hood, Nancy E.; Colabianchi, Natalie; Terry-McElrath, Yvonne M.; O'Malley, Patrick M.; Johnston, Lloyd D.

2014-01-01

Background: Research on physical activity breaks and facilities (indoor and outdoor) in secondary schools is relatively limited. Methods: School administrators and students in nationally representative samples of 8th (middle school) and 10th/12th grade (high school) students were surveyed annually from 2008-2009 to 2011-2012. School administrators…

Bend or Break: Your IQ Is Not Your Identity

ERIC Educational Resources Information Center

Hasan, Melissa R

2013-01-01

Melissa Hasan believes that Conceptual Physics saved her sanity. A seemingly unimportant metallurgical fact she learned in high school has made parenting her toddler possible on most days. The most important thing she learned in High School from Conceptual Physics, and Interpersonal Relationships was that what is rigid breaks. In high school, she…

Which population groups are most unaware of CVD risks associated with sitting time?

PubMed

Duncan, Mitch J; Gilson, Nicholas; Vandelanotte, Corneel

2014-08-01

Prolonged sitting is an emerging risk factor for poor health yet few studies have examined awareness of the risks associated with sitting behaviours. This study identifies the population subgroups with the highest levels of unawareness regarding the cardiovascular disease (CVD) risks associated with sitting behaviours. Adults (n=1256) living in Queensland, Australia completed a telephone-based survey in 2011, analysis conducted in 2013. The survey assessed participant's socio-demographic characteristics, physical activity, sitting behaviours and awareness of CVD risks associated with three sitting behaviours: 1) sitting for prolonged periods, 2), sitting for prolonged periods whilst also engaging in regular physical activity, and 3) breaking up periods of prolonged sitting with short activity breaks. Population sub-groups with the highest levels of unawareness were identified based on socio-demographic and behavioural characteristics using signal detection analysis. Unawareness ranged from 23.3% to 67.0%. Age was the most important variable in differentiating awareness levels; younger adults had higher levels of unawareness. Body mass index, physical activity, TV viewing, employment status and time spent at work also identified population sub-groups. Unawareness of CVD risk for prolonged sitting was moderately high overall. Younger adults had high levels of unawareness on all of the outcomes examined. Copyright © 2014 Elsevier Inc. All rights reserved.

Waiting for the W and the Higgs

DOE PAGES

Tannenbaum, Michael J.

2016-10-06

The search for the left-handed W± bosons, the proposed quanta of the weak interaction, and the Higgs boson, which spontaneously breaks the symmetry of unification of electromagnetic and weak interactions, has driven elementary-particle physics research from the time that I entered college to the present and has led to many unexpected and exciting discoveries which revolutionized our view of subnuclear physics over that period. In this article I describe how these searches and discoveries have intertwined with my own career.

Waiting for the W. and the Higgs

NASA Astrophysics Data System (ADS)

Tannenbaum, M. J.

2016-12-01

The search for the left-handed W± bosons, the proposed quanta of the weak interaction, and the Higgs boson, which spontaneously breaks the symmetry of unification of electromagnetic and weak interactions, has driven elementary-particle physics research from the time that I entered college to the present and has led to many unexpected and exciting discoveries which revolutionized our view of subnuclear physics over that period. In this article I describe how these searches and discoveries have intertwined with my own career.

Breaking news dissemination in the media via propagation behavior based on complex network theory

NASA Astrophysics Data System (ADS)

Liu, Nairong; An, Haizhong; Gao, Xiangyun; Li, Huajiao; Hao, Xiaoqing

2016-07-01

The diffusion of breaking news largely relies on propagation behaviors in the media. The tremendous and intricate propagation relationships in the media form a complex network. An improved understanding of breaking news diffusion characteristics can be obtained through the complex network research. Drawing on the news data of Bohai Gulf oil spill event from June 2011 to May 2014, we constructed a weighted and directed complex network in which media are set as nodes, the propagation relationships as edges and the propagation times as the weight of the edges. The primary results show (1) the propagation network presents small world feature, which means relations among media are close and breaking news originating from any node can spread rapidly; (2) traditional media and official websites are the typical sources for news propagation, while business portals are news collectors and spreaders; (3) the propagation network is assortative and the group of core media facilities the spread of breaking news faster; (4) for online media, news originality factor become less important to propagation behaviors. This study offers a new insight to explore information dissemination from the perspective of statistical physics and is beneficial for utilizing the public opinion in a positive way.

Optimization of the Switch Mechanism in a Circuit Breaker Using MBD Based Simulation

PubMed Central

Jang, Jin-Seok; Yoon, Chang-Gyu; Ryu, Chi-Young; Kim, Hyun-Woo; Bae, Byung-Tae; Yoo, Wan-Suk

2015-01-01

A circuit breaker is widely used to protect electric power system from fault currents or system errors; in particular, the opening mechanism in a circuit breaker is important to protect current overflow in the electric system. In this paper, multibody dynamic model of a circuit breaker including switch mechanism was developed including the electromagnetic actuator system. Since the opening mechanism operates sequentially, optimization of the switch mechanism was carried out to improve the current breaking time. In the optimization process, design parameters were selected from length and shape of each latch, which changes pivot points of bearings to shorten the breaking time. To validate optimization results, computational results were compared to physical tests with a high speed camera. Opening time of the optimized mechanism was decreased by 2.3 ms, which was proved by experiments. Switch mechanism design process can be improved including contact-latch system by using this process. PMID:25918740

Classroom-Based Physical Activity Breaks and Children's Attention: Cognitive Engagement Works!

PubMed Central

Schmidt, Mirko; Benzing, Valentin; Kamer, Mario

2016-01-01

Classroom-based physical activity breaks are postulated to positively impact children's attention during their school day. However, empirical evidence for this claim is scarce and the role of cognitive engagement in enhancing children's attentional performance is unexplored in studies on physical activity breaks. The aim of the present study was therefore to disentangle the separate and/or combined effects of physical exertion and cognitive engagement induced by physical activity breaks on primary school children's attention. In addition, the role of children's affective reactions to acute interventions at school was investigated. Using a 2 × 2 between-subjects experimental design, 92 children between the ages of 11 and 12 years (M = 11.77, SD = 0.41) were randomly assigned to one of four experimental conditions: (1) combo group (physical activity with high cognitive demands), (2) cognition group (sedentary with high cognitive demands), (3) physical group (physical activity with low cognitive demands), and (4) control group (sedentary with low cognitive demands). Attention and affect were measured before and immediately after a 10-min intervention. ANCOVAs revealed that whereas physical exertion had no effect on any measure of children's attentional performance, cognitive engagement was the crucial factor leading to increased focused attention and enhanced processing speed. Mediational analyses showed that changes in positive affect during the interventions mediated the effect between cognitive engagement and focused attention as well as between cognitive engagement and processing speed. These surprising results are discussed in the light of theories predicting both facilitating and deteriorative effects of positive affect on attention. PMID:27757088

Goldstone mode and pair-breaking excitations in atomic Fermi superfluids

NASA Astrophysics Data System (ADS)

Hoinka, Sascha; Dyke, Paul; Lingham, Marcus G.; Kinnunen, Jami J.; Bruun, Georg M.; Vale, Chris J.

2017-10-01

Spontaneous symmetry breaking is a central paradigm of elementary particle physics, magnetism, superfluidity and superconductivity. According to Goldstone's theorem, phase transitions that break continuous symmetries lead to the existence of gapless excitations in the long-wavelength limit. These Goldstone modes can become the dominant low-energy excitation, showing that symmetry breaking has a profound impact on the physical properties of matter. Here, we present a comprehensive study of the elementary excitations in a homogeneous strongly interacting Fermi gas through the crossover from a Bardeen-Cooper-Schrieffer (BCS) superfluid to a Bose-Einstein condensate (BEC) of molecules using two-photon Bragg spectroscopy. The spectra exhibit a discrete Goldstone mode, associated with the broken-symmetry superfluid phase, as well as pair-breaking single-particle excitations. Our techniques yield a direct determination of the superfluid pairing gap and speed of sound in close agreement with strong-coupling theories.

Effects of garlic on cellular doubling time and DNA strand breaks caused by UV light and BPL, enhanced with catechol and TPA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baturay, N.Z.; Gayle, F.; Liu, S.

1995-11-01

3T3 cell cultures were exposed to UV light and Beta-Propiolactone. Neoplastic cell transformation (TF) was demonstrated after concurrent addition of catechol, or repeated addition of TPA. Addition of garlic to all fluences/concentrations of the carcinogen/cocarcinogen/promoter groups reduced the number of transformed foci/dish by at least 40%. Since the cell cycle is prolonged following exposure to carcinogens, it is likely the cell requires a longer time to repair this damage. The doubling time (DT) was extended from 12 to 36 hrs. when cells were exposed to BPL and from 12 o 28 hrs. when cells were exposed to 3.0J/M2/sec. If anmore » anticarcinogenic compound is also added, it is reasonable to assume that the cell cycle may be further elongated. The cell cycle, denoted by DT was lengthened from 12 to 47 hrs and from 12 to 86 hrs for BPL and UVC, respectively. The extensions occurred in a dope dependent manner. The concentrations of the cocarcinogen and promoter remained constant throughout the experiment. When strand breaks were determined at the same dose sequences, by alkaline elution, more repair was seen with garlic where the lowest and middle doses of BPL were used and almost no decrease in % DNA eluted was seen with UVC exposed cells. With catechol, there was a two-fold decrease in % DNA eluted at the lowest and middle fluences. When TPA was added, all three fluences of UVC showed more than a threefold decrease in % DNA eluted. BPS with both TPA and catechol, again showed a reduction in strand breaks only low and middle doses. Both a direct-acting alkylating agent, BPL, and a physical carcinogen, UVC, were homogeneously affected, in terms of doubling time, but not when strand break repair was examined. A separate mechanism may be responsible for repair, and the mechanism associated with combinations of physical carcinogen enhancing agents combined with some non-carcinogens may be more profoundly affected by some natural products.« less

Physical Activity Breaks and Student Learning: A Teacher-Research Project

ERIC Educational Resources Information Center

Camahalan, Faye Marsha G.; Ipock, Amanda R.

2015-01-01

This study is a teacher initiated action research. The purpose is to improve student learning in math using physical activity breaks during classroom lessons. The study was conducted by tracking the results of ten 5th grade students for a period of one week. Using anecdotal notes, students showed improvement on attentiveness during class…

Promoting Physical Activity in Elementary Schools: Needs Assessment and a Pilot Study of Brain Breaks

ERIC Educational Resources Information Center

Perera, Thushanthi; Frei, Simone; Frei, Balz; Bobe, Gerd

2015-01-01

A sedentary life style contributes to many chronic diseases and poor educational performance. Since elementary school-aged children spend most wakeful hours in school, classroom teachers are essential for providing physical activity (PA) breaks during school. As first objective, we assessed current PA levels for Oregon public elementary schools…

Getting Rid of Gravity--Alternative Ways of Looking at Trajectories

ERIC Educational Resources Information Center

Dion, Peter W.; Ho, Anthony M. H.

2010-01-01

Problems in projectile motion are a time-honored staple of high school and even first-year university physics. They can become confusing for some students, yet boring for the stronger students. Herein we present two alternative approaches to such questions, one we call "breaking down gravity," which makes these questions easier to solve, and the…

M. Hildred Blewett and the Blewett Scholarship

NASA Astrophysics Data System (ADS)

Whitten, Barbara

2011-03-01

M. Hildred Blewett became a physicist at a time when few women were physicists. After beginning her career at General Electric, she became a respected accelerator physicist, working at Brookhaven, Argonne, and eventually CERN. Blewett was married for a time to John Blewett, another accelerator physicist, but the couple divorced without children and she never remarried. She felt that her career in physics was hampered by her gender, and when she died in 2004 at the age of 93, she left the bulk of her estate to the American Physical Society, to found a Scholarship for women in physics. Since 2005 the Blewett Scholarship has been awarded to women in physics who are returning to physics after a career break, usually for family reasons. Family/career conflicts are one of the most important reasons why young women in early careers leave physics---a loss for them as well as the physics community, which has invested time and money in their training. The Blewett Scholarship is one way for the physics community, under the leadership of CSWP, to help these young women resume their careers. I will discuss the life and work of Hildred Blewett, the Blewett Scholarship, and its benefits to the physics community.

Quantitative, non-invasive imaging of radiation-induced DNA double strand breaks in vivo

PubMed Central

Li, Wenrong; Li, Fang; Huang, Qian; Shen, Jingping; Wolf, Frank; He, Yujun; Liu, Xinjian; Hu, Y. Angela; Bedford, Joel. S.; Li, Chuan-Yuan

2011-01-01

DNA double strand breaks is a major form of DNA damage and a key mechanism through which radiotherapy and some chemotherapeutic agents kill cancer cells. Despite its importance, measuring DNA double strand breaks is still a tedious task that is normally carried out by gel electrophoresis or immunofluorescence staining. Here we report a novel approach to image and quantify DNA double strand breaks in live mammalian cells through bi-fragment luciferase reconstitution. N- and C- terminal fragments of firefly luciferase gene were fused with H2AX and MDC1 genes, respectively. Our strategy was based on the established fact that at the sites of DNA double strand breaks, H2AX protein is phosphoryated and physically associates with the MDC1 protein, thus bringing together N- and C- luciferase fragments and reconstituting luciferase activity. Our strategy allowed serial, non-invasive quantification of DNA double strand breaks in cells irradiated with x-rays and 56Fe ions. Furthermore, it allowed for the evaluation of DNA double strand breaks (DSBs) non-invasively in vivo in irradiated tumors over two weeks. Surprisingly, we detected a second wave of DSB induction in irradiated tumor cells days after radiation exposure in addition to the initial rapid induction of DSBs. We conclude that our new split-luciferase based method for imaging γ-H2AX-MDC1 interaction is a powerful new tool to study DNA double strand break repair kinetics in vivo with considerable advantage for experiments requiring observations over an extended period of time. PMID:21527553

R-Axion: A New LHC Physics Signature Involving Muon Pairs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goh, Hock-Seng; /UC, Berkeley /LBL, Berkeley; Ibe, Masahiro

2012-04-12

In a class of models with gauge mediated supersymmetry breaking, the existence of a light pseudo scalar particle, R-axion, with a mass in hundreds MeV range is predicted. The striking feature of such a light R-axion is that it mainly decays into a pair of muons and leaves a displaced vertex inside detectors once it is produced. In this talk, we show how we can search for the R-axion at the coming LHC experiments. The one main goal of the LHC experiments is discovering supersymmetry which has been anticipated for a long time to solve the hierarchy problem. Once themore » supersymmetric standard model (SSM) is confirmed experimentally, the next question is how the supersymmetry is broken and how the effects of symmetry breaking are mediated to the SSM sector. In most cases, such investigations on 'beyond the SSM physics' rely on arguments based on extrapolations of the observed supersymmetry mass parameters to higher energies. However, there is one class of models of supersymmetry breaking where we can get a direct glimpse of the structure of the hidden sector with the help of the R-symmetry. The R-symmetry plays an important role in rather generic models of spontaneous supersymmetry breaking. At the same time, however, it must be broken in some way in order for the gauginos in the SSM sector to have non-vanishing masses. One possibility of the gaugino mass generation is to consider models where the gaugino masses are generated as a result of the explicit breaking of the R-symmetries. Unfortunately, in those models, the R-symmetry leaves little trace for the collider experiments, since the mass of the R-axion is typically heavy and beyond the reach of the LHC experiments. In this talk, instead, we consider a class of models with gauge mediation where the R-symmetry in the hidden/messenger sectors is exact in the limit of the infinite reduced Planck scale, i.e. M{sub PL} {yields} {infinity}. In this case, the gaugino masses are generated only after the R-symmetry is broken spontaneously. We also assume that the R-symmetry is respected by the SSM sector as well as the origin of the higgsino mass {mu} and the Higgs mass mixing B{mu} at the classical level. We call this scenario, the minimal R-symmetry breaking scenario.« less

Effectiveness of two Arthritis Foundation programs: Walk With Ease, and YOU Can Break the Pain Cycle

PubMed Central

Bruno, Michelle; Cummins, Susan; Gaudiano, Lisha; Stoos, Johanna; Blanpied, Peter

2006-01-01

Objective: To evaluate the effectiveness of two Arthritis Foundation programs: Walk With Ease (WWE) and YOU Can Break The Pain Cycle (PC). Design: Quasi-experimental, repeated measures design. Retested at six weeks and four months. Setting: Community based intervention. Participants: Volunteer sample of 163 adults with arthritis recruited through mailings, newspapers, and flyers. Interventions: Subjects participated in a 90 minute seminar (PC, Group A), a six-week walking program (WWE, Group B), or both programs (Group C). Main outcome measures: Survey assessment of arthritis knowledge, general health, self-management activities, confidence, physical abilities, depression, health distress, and how arthritis affects their life. A Squat Test, a Six Minute Walk test, and a Timed Functional Walk Test were also administered. Results: Subjects in Group B were more confident, less depressed, had less health distress, and less pain than subjects in Group A. Scores of Group C were between Group A and B scores. Differences in groups over time indicated that the WWE resulted in increased confidence, physical abilities, time spent in self-management activities and decreased pain and fatigue. All groups increased in walking endurance at six weeks, and increased in health distress at four months. Conclusion: Subjects in different programs differed on impact of arthritis. These programs provide effective arthritis management opportunities. PMID:18046884

Summer Session: A Time for Innovation

NASA Astrophysics Data System (ADS)

Mola, Monty

2013-05-01

Summer is almost here (at least for those of us who teach semesters). Many of us are taking a well-deserved break to spend time with our families, conduct research, travel, and myriad other activities. Some of us, however, will be teaching summer school. For those of us lucky enough to be teaching this summer, we have one suggestion: Be bold! Summer is the ideal time to try something new with your teaching. We have known for some time that alternative pedagogies and engaging teaching strategies can be more effective than traditional lectures as student learning environments. However, even with headlines in The Washington Post proclaiming that the lecture is dead,2 inroads of physics education research-based curricula have been slow to diffuse into the classrooms for the greater population of college physics instructors.3 Many instructors of traditional physics courses see the use of research-based instructional strategies (RBIS) as desirable but risky and time consuming.3 Assuming a traditional physics course structure, both the where and the when each component takes place can also limit the types of engaging pedagogies used.4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Jiang-Hao

In original twin Higgs model, vacuum misalignment between electroweak and new physics scales is realized by adding explicit Z 2 breaking term. Introducing additional twin Higgs could accommodate spontaneous Z 2 breaking, which explains origin of this misalignment. We introduce a class of twin two Higgs doublet models with most general scalar potential, and discuss general conditions which trigger electroweak and Z 2 symmetry breaking. Various scenarios on realising the vacuum misalignment are systematically discussed in a natural composite two Higgs double model framework: explicit Z 2 breaking, radiative Z 2 breaking, tadpole-induced Z 2 breaking, and quartic-induced Z 2more » breaking. Finally, we investigate the Higgs mass spectra and Higgs phenomenology in these scenarios.« less

Role of the lens in controlling physical dormancy break and germination of Delonix regia (Fabaceae: Caesalpinioideae).

PubMed

Jaganathan, G K; Wu, G-R; Han, Y-Y; Liu, B L

2017-01-01

Physical dormancy occurs in all three subfamilies of Fabaceae, namely Mimosoideae, Papilionoideae and Caesalpinioideae, making it one of the largest plant families in terms of number of species with physical dormancy. However, little is known about the water gap structure and germination ecology of species in Caesalpinioideae. Freshly collected seeds of Delonix regia (Caesalpinioideae) did not imbibe water, thus they had physical dormancy. Both dry heat and wet heat were effective in breaking dormancy, however, longer duration was required at 80 °C and shorter duration at 90 °C. Seeds buried in the field for 2 years germinated to 21% and 42% after the first and second summer, respectively, compared with 3% germination in seeds at the time of maturity. Seeds incubated at 15/60 °C in the laboratory (mimicking summer conditions) for 3 months supported this conclusion, as dormancy was relieved in 18% and 24% of seeds stored dry and watered intermediately, respectively. All the dormancy breaking treatments resulted in lifting of palisade layers in the lens region to form a circular lid-like opening, i.e. water gap (Type II simple). Blocking experiments confirmed that water entered only through the lens and no secondary water entry point was observed. No apparent changes in morphology/anatomy of the hilum region were noted in dormant and non-dormant (water permeable) seeds. These results suggest that summer temperatures could open the lens in a proportion of seeds every year and that germination occurs during the subsequent wet season in the tropics. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

Spontaneous Time Symmetry Breaking in System with Mixed Strategy Nash Equilibrium: Evidences in Experimental Economics Data

NASA Astrophysics Data System (ADS)

Wang, Zhijian; Xu, Bin; Zhejiang Collaboration

2011-03-01

In social science, laboratory experiment with human subjects' interaction is a standard test-bed for studying social processes in micro level. Usually, as in physics, the processes near equilibrium are suggested as stochastic processes with time-reversal symmetry (TRS). To the best of our knowledge, near equilibrium, the breaking time symmetry, as well as the existence of robust time anti-symmetry processes, has not been reported clearly in experimental economics till now. By employing Markov transition method to analysis the data from human subject 2x2 Games with wide parameters and mixed Nash equilibrium, we study the time symmetry of the social interaction process near Nash equilibrium. We find that, the time symmetry is broken, and there exists a robust time anti-symmetry processes. We also report the weight of the time anti-symmetry processes in the total processes of each the games. Evidences in laboratory marketing experiments, at the same time, are provided as one-dimension cases. In these cases, time anti-symmetry cycles can also be captured. The proposition of time anti-symmetry processes is small, but the cycles are distinguishable.

Associations of sedentary behavior, sedentary bouts and breaks in sedentary time with cardiometabolic risk in children with a family history of obesity.

PubMed

Saunders, Travis John; Tremblay, Mark Stephen; Mathieu, Marie-Ève; Henderson, Mélanie; O'Loughlin, Jennifer; Tremblay, Angelo; Chaput, Jean-Philippe

2013-01-01

Although reports in adults suggest that breaks in sedentary time are associated with reduced cardiometabolic risk, these findings have yet to be replicated in children. To investigate whether objectively measured sedentary behavior, sedentary bouts or breaks in sedentary time are independently associated with cardiometabolic risk in a cohort of Canadian children aged 8-11 years with a family history of obesity. Data from 286 boys and 236 girls living in Quebec, Canada, with at least one biological parent with obesity (QUALITY cohort) were collected from 2005-2008, and analyzed in 2013. Sedentary behavior, light and moderate-to-vigorous physical activity were measured over 7 days using accelerometry. Leisure time computer/video game use and TV viewing over the past 7 days were self-reported. Outcomes included waist circumference, body mass index Z-score, fasting insulin, fasting glucose, triglycerides, HDL-cholesterol, C-reactive protein and a continuous cardiometabolic risk score. After adjustment for confounders, breaks in sedentary time and the number of sedentary bouts lasting 1-4 minutes were associated with reduced cardiometabolic risk score and lower BMI Z-score in both sexes (all p<0.05). The number of sedentary bouts lasting 5-9 minutes was negatively associated with waist circumference in girls only, while the number of bouts lasting 10-14 minutes was positively associated with fasting glucose in girls, and with BMI Z-score in boys (all p<0.05). Leisure time computer/video game use was associated with increased cardiometabolic risk score and waist circumference in boys, while TV viewing was associated with increased cardiometabolic risk, waist circumference, and BMI Z-score in girls (all p<0.05). These results suggest that frequent interruptions in sedentary time are associated with a favourable cardiometabolic risk profile and highlight the deleterious relationship between screen time and cardiometabolic risk among children with a family history of obesity.

River-ice break-up/freeze-up: a review of climatic drivers, historical trends and future predictions

NASA Astrophysics Data System (ADS)

Prowse, T. D.; Bonsal, B. R.; Duguay, C. R.; Lacroix, M. P.

2007-10-01

River ice plays a fundamental role in biological, chemical and physical processes that control freshwater regimes of the cold regions. Moreover, it can have enormous economic implications for river-based developments. All such activities and processes can be modified significantly by any changes to river-ice thickness, composition or event timing and severity. This paper briefly reviews some of the major hydraulic, mechanical and thermodynamic processes controlling river-ice events and how these are influenced by variations in climate. A regional and temporal synthesis is also made of the observed historical trends in river-ice break-up/freeze-up occurrence from the Eurasian and North American cold regions. This involves assessment of several hydroclimatic variables that have influenced past trends and variability in river-ice break-up/freeze-up dates including air-temperature indicators (e.g. seasonal temperature, 0°C isotherm dates and various degree-days) and large-scale atmospheric circulation patterns or teleconnections. Implications of future climate change on the timing and severity of river-ice events are presented and discussed in relation to the historical trends. Attention is drawn to the increasing trends towards the occurrence of mid-winter break-up events that can produce especially severe flood conditions but prove to be the most difficult type of event to model and predict.

The highest-ranking rooster has priority to announce the break of dawn.

PubMed

Shimmura, Tsuyoshi; Ohashi, Shosei; Yoshimura, Takashi

2015-07-23

The "cock-a-doodle-doo" crowing of roosters, which symbolizes the break of dawn in many cultures, is controlled by the circadian clock. When one rooster announces the break of dawn, others in the vicinity immediately follow. Chickens are highly social animals, and they develop a linear and fixed hierarchy in small groups. We found that when chickens were housed in small groups, the top-ranking rooster determined the timing of predawn crowing. Specifically, the top-ranking rooster always started to crow first, followed by its subordinates, in descending order of social rank. When the top-ranking rooster was physically removed from a group, the second-ranking rooster initiated crowing. The presence of a dominant rooster significantly reduced the number of predawn crows in subordinates. However, the number of crows induced by external stimuli was independent of social rank, confirming that subordinates have the ability to crow. Although the timing of subordinates' predawn crowing was strongly dependent on that of the top-ranking rooster, free-running periods of body temperature rhythms differed among individuals, and crowing rhythm did not entrain to a crowing sound stimulus. These results indicate that in a group situation, the top-ranking rooster has priority to announce the break of dawn, and that subordinate roosters are patient enough to wait for the top-ranking rooster's first crow every morning and thus compromise their circadian clock for social reasons.

A unified spectral parameterization for wave breaking: From the deep ocean to the surf zone

NASA Astrophysics Data System (ADS)

Filipot, J.-F.; Ardhuin, F.

2012-11-01

A new wave-breaking dissipation parameterization designed for phase-averaged spectral wave models is presented. It combines wave breaking basic physical quantities, namely, the breaking probability and the dissipation rate per unit area. The energy lost by waves is first explicitly calculated in physical space before being distributed over the relevant spectral components. The transition from deep to shallow water is made possible by using a dissipation rate per unit area of breaking waves that varies with the wave height, wavelength and water depth. This parameterization is implemented in the WAVEWATCH III modeling framework, which is applied to a wide range of conditions and scales, from the global ocean to the beach scale. Wave height, peak and mean periods, and spectral data are validated using in situ and remote sensing data. Model errors are comparable to those of other specialized deep or shallow water parameterizations. This work shows that it is possible to have a seamless parameterization from the deep ocean to the surf zone.

Parametric Symmetry Breaking in a Nonlinear Resonator

NASA Astrophysics Data System (ADS)

Leuch, Anina; Papariello, Luca; Zilberberg, Oded; Degen, Christian L.; Chitra, R.; Eichler, Alexander

2016-11-01

Much of the physical world around us can be described in terms of harmonic oscillators in thermodynamic equilibrium. At the same time, the far-from-equilibrium behavior of oscillators is important in many aspects of modern physics. Here, we investigate a resonating system subject to a fundamental interplay between intrinsic nonlinearities and a combination of several driving forces. We have constructed a controllable and robust realization of such a system using a macroscopic doubly clamped string. We experimentally observe a hitherto unseen double hysteresis in both the amplitude and the phase of the resonator's response function and present a theoretical model that is in excellent agreement with the experiment. Our work unveils that the double hysteresis is a manifestation of an out-of-equilibrium symmetry breaking between parametric phase states. Such a fundamental phenomenon, in the most ubiquitous building block of nature, paves the way for the investigation of new dynamical phases of matter in parametrically driven many-body systems and motivates applications ranging from ultrasensitive force detection to low-energy computing memory units.

Deconvolution of acoustic emissions for source localization using time reverse modeling

NASA Astrophysics Data System (ADS)

Kocur, Georg Karl

2017-01-01

Impact experiments on small-scale slabs made of concrete and aluminum were carried out. Wave motion radiated from the epicenter of the impact was recorded as voltage signals by resonant piezoelectric transducers. Numerical simulations of the elastic wave propagation are performed to simulate the physical experiments. The Hertz theory of contact is applied to estimate the force impulse, which is subsequently used for the numerical simulation. Displacements at the transducer positions are calculated numerically. A deconvolution function is obtained by comparing the physical (voltage signal) and the numerical (calculated displacement) experiments. Acoustic emission signals due to pencil-lead breaks are recorded, deconvolved and applied for localization using time reverse modeling.

Physical activity and sedentary time: male perceptions in a university work environment.

PubMed

George, Emma S; Kolt, Gregory S; Rosenkranz, Richard R; Guagliano, Justin M

2014-03-01

Promoting physical activity and reducing sedentary time in males can be challenging, and interventions tailored specifically for males are limited. Understanding male perceptions of physical activity and sedentary behavior is important to inform development of relevant interventions, especially for males working in an office setting. As part of a larger intervention study to increase physical activity and reduce sedentary time, male university employees aged 35 to 64 years were invited to partake in focus groups to discuss benefits, motivators, and barriers related to physical activity and sedentary time. Five semistructured focus group sessions, ranging from 50 to 70 minutes in duration, were conducted on two campuses at an Australian university. A total of 15 participants (9 academic/faculty staff and 6 professional staff), with a mean (± SD) age of 46.1 (±8.0) years took part in the study. Health and family were commonly discussed motivators for physical activity, whereas time constraints and work commitments were major barriers to physical activity participation. Sedentary time was a perceived "by-product" of participants' university employment, as a substantial proportion of their days were spent sitting, primarily at a computer. Participants believed that physical activity should be recognized as a legitimate activity at work, embedded within the university culture and endorsed using a top-down approach. It is important to encourage breaks in sedentary time and recognize physical activity as a legitimate health-promoting activity that is supported and encouraged during working hours. These findings can be used as a platform from which to develop targeted strategies to promote physical activity in male university employees.

A tale of twin Higgs: natural twin two Higgs doublet models

DOE PAGES

Yu, Jiang-Hao

2016-12-28

In original twin Higgs model, vacuum misalignment between electroweak and new physics scales is realized by adding explicit Z 2 breaking term. Introducing additional twin Higgs could accommodate spontaneous Z 2 breaking, which explains origin of this misalignment. We introduce a class of twin two Higgs doublet models with most general scalar potential, and discuss general conditions which trigger electroweak and Z 2 symmetry breaking. Various scenarios on realising the vacuum misalignment are systematically discussed in a natural composite two Higgs double model framework: explicit Z 2 breaking, radiative Z 2 breaking, tadpole-induced Z 2 breaking, and quartic-induced Z 2more » breaking. Finally, we investigate the Higgs mass spectra and Higgs phenomenology in these scenarios.« less

Factors associated with sports-related dental injuries among young athletes: a cross-sectional study in Miyagi prefecture.

PubMed

Tsuchiya, Shinobu; Tsuchiya, Masahiro; Momma, Haruki; Sekiguchi, Takuya; Kuroki, Kaoru; Kanazawa, Kenji; Koseki, Takeyoshi; Igarashi, Kaoru; Nagatomi, Ryoichi; Hagiwara, Yoshihiro

2017-12-29

Sports-related dental injuries, such as tooth fracture, loosening, and avulsion, are a major concern among young athletes because they directly impair oral function. Although the preventive efficacy of mouthguards has been well established, the prevalence of sports-related dental injuries remains high among young athletes. The aim of this study is to identify the variables contributing to the risk of sports-related dental injuries by conducting a survey on large population of young athletes in Miyagi prefecture. A cross-sectional study was conducted with school-aged athletes (aged 6-15 years, n = 5735) using a self-reported questionnaire. The questionnaire examined general variables, including sex, age, and body mass index; sports-related variables, including sports-type, team level, activity schedule, break time, and verbal/physical abuse by coaches; and lifestyle variables related to free time, including screen-time and sleep duration. Their associations with sports-related dental injuries were examined using multivariate logistic regression models. The prevalence of sports-related dental injuries was 13.3% (763 of 5735 young athletes) and was higher in males (14.3%, 592 of 4132) than in females (10.7%, 171 of 1603; adjusted odds ratios [ORs] and 95% confidence intervals [CIs]: 1.48 [1.22-1.79], p < 0.001). After stratification according to sex, significant associations with the prevalence of sports-related dental injuries were evident for three variables-insufficient break time, verbal abuse, and physical punishment-in males (adjusted ORs [95% CI]: 1.35 [1.03-1.77], p = 0.032; 1.31 [1.05-1.62], p = 0.015; and 1.36 [1.06-1.75], p = 0.016, respectively) but not in females (adjusted ORs [95% CI]: 0.88 [0.53-1.47], p = 0.623; 1.29 [0.87-1.91], p = 0.206; and 0.97 [0.57-1.63], p = 0.894, respectively). Although our results might be based on the individual athlete's self-perception to the sports-related variables, our results suggest that insufficient break time, verbal abuse, and physical punishment from coaches are positively associated with the prevalence of sports-related dental injuries in young male athletes.

Impact of SCBA size and firefighting work cycle on firefighter functional balance.

PubMed

Kesler, Richard M; Deetjen, Grace S; Bradley, Faith F; Angelini, Michael J; Petrucci, Matthew N; Rosengren, Karl S; Horn, Gavin P; Hsiao-Wecksler, Elizabeth T

2018-05-01

Slips, trips and falls are leading causes of fireground injuries. A functional balance test (FBT) was used to investigate the effects of self-contained breathing apparatus (SCBA) size and design, plus firefighting work cycle. During the FBT, subjects walked along a narrow platform and turned in defined spaces, with and without an overhead obstacle. Thirty firefighters wore three varying-sized standard SCBAs and a low-profile prototype SCBA during three simulated firefighting work/rest cycles. Firefighters were tested pre- and post-firefighting activity (one bout, two bouts with a 5-min break, or back-to-back bouts with no break). Subjects committed more errors and required longer completion times with larger SCBAs. Use of the prototype SCBA lead to lower times and fewer errors. Performing a second bout of firefighting increased completion time. Firefighters need to consider how SCBA and amount of physical activity on the fireground may influence balance in order to reduce the risk of injury. Copyright © 2018 Elsevier Ltd. All rights reserved.

Systematic review of acute physically active learning and classroom movement breaks on children's physical activity, cognition, academic performance and classroom behaviour: understanding critical design features.

PubMed

Daly-Smith, Andy J; Zwolinsky, Stephen; McKenna, Jim; Tomporowski, Phillip D; Defeyter, Margaret Anne; Manley, Andrew

2018-01-01

To examine the impact of acute classroom movement break (CMB) and physically active learning (PAL) interventions on physical activity (PA), cognition, academic performance and classroom behaviour. Systematic review. PubMed, EBSCO, Academic Search Complete, Education Resources Information Center, PsycINFO, SPORTDiscus, SCOPUS and Web of Science. Studies investigating school-based acute bouts of CMB or PAL on (PA), cognition, academic performance and classroom behaviour. The Downs and Black checklist assessed risk of bias. Ten PAL and eight CMB studies were identified from 2929 potentially relevant articles. Risk of bias scores ranged from 33% to 64.3%. Variation in study designs drove specific, but differing, outcomes. Three studies assessed PA using objective measures. Interventions replaced sedentary time with either light PA or moderate-to-vigorous PA dependent on design characteristics (mode, duration and intensity). Only one study factored individual PA outcomes into analyses. Classroom behaviour improved after longer moderate-to-vigorous (>10 min), or shorter more intense (5 min), CMB/PAL bouts (9 out of 11 interventions). There was no support for enhanced cognition or academic performance due to limited repeated studies. Low-to-medium quality designs predominate in investigations of the acute impacts of CMB and PAL on PA, cognition, academic performance and classroom behaviour. Variable quality in experimental designs, outcome measures and intervention characteristics impact outcomes making conclusions problematic. CMB and PAL increased PA and enhanced time on task. To improve confidence in study outcomes, future investigations should combine examples of good practice observed in current studies. CRD42017070981.

Effects of pH and Salts on Physical and Mechanical Properties of Pea Starch Films.

PubMed

Choi, W S; Patel, D; Han, J H

2016-07-01

To identify the significant contribution of intermolecular hydrogen bonds of starch molecules to the film structure formation, pH of film-forming solutions was adjusted and also various salts (NaCl, CaCl2 , CaSO4 , and K2 SO4 ) were mixed into the glycerol-plasticized pea starch film. The film made from pH 7 possessed the highest tensile strength-at-break (2 times) and elastic modulus (4 to 15 times) and the lowest elongation-at-break compared with those of the films made from acid and alkali environments. The pH 7 film also has the highest film density and the lowest total soluble matter. At the level of 0.01 to 0.1 M of CaSO4 and 0.1 M of K2 SO4 in a kilogram of starch, the water solubility of the film increased, while chloride salts slightly lowered the solubility. NaCl and CaSO4 reduced water vapor permeability (WVP), while CaCl2 slightly increased WVP at 0.01 and 0.06 M concentrations, and K2 SO4 significantly increased WVP at 0.03 and 0.15 M. Presence of salts increased tensile strength (5 to 14 times than the control films) and elastic modulus (35 to 180 times) of starch film at 0.01 to 0.03 M of CaSO4 and K2 SO4 . Elongation-at-break increased significantly as salt concentration increases to an optimal level. However, when the concentration exceeded above the optimal level, the E of starch films decreased and showed no significant difference from the control film. Overall, the addition of salts modified physical and mechanical properties of pea starch films more than pH adjustment without any salt addition. © 2016 Institute of Food Technologists®

Null geodesics and wave front singularities in the Gödel space-time

NASA Astrophysics Data System (ADS)

Kling, Thomas P.; Roebuck, Kevin; Grotzke, Eric

2018-01-01

We explore wave fronts of null geodesics in the Gödel metric emitted from point sources both at, and away from, the origin. For constant time wave fronts emitted by sources away from the origin, we find cusp ridges as well as blue sky metamorphoses where spatially disconnected portions of the wave front appear, connect to the main wave front, and then later break free and vanish. These blue sky metamorphoses in the constant time wave fronts highlight the non-causal features of the Gödel metric. We introduce a concept of physical distance along the null geodesics, and show that for wave fronts of constant physical distance, the reorganization of the points making up the wave front leads to the removal of cusp ridges.

A Study of ATLAS Grid Performance for Distributed Analysis

NASA Astrophysics Data System (ADS)

Panitkin, Sergey; Fine, Valery; Wenaus, Torre

2012-12-01

In the past two years the ATLAS Collaboration at the LHC has collected a large volume of data and published a number of ground breaking papers. The Grid-based ATLAS distributed computing infrastructure played a crucial role in enabling timely analysis of the data. We will present a study of the performance and usage of the ATLAS Grid as platform for physics analysis in 2011. This includes studies of general properties as well as timing properties of user jobs (wait time, run time, etc). These studies are based on mining of data archived by the PanDA workload management system.

Single particles accelerate final stages of capillary break-up

NASA Astrophysics Data System (ADS)

Lindner, Anke; Fiscina, Jorge Eduardo; Wagner, Christian

2015-06-01

Droplet formation of suspensions is present in many industrial and technological processes such as coating and food engineering. Whilst the finite-time singularity of the minimum neck diameter in capillary break-up of simple liquids can be described by well-known self-similarity solutions, the pinching of non-Brownian suspension depends in a complex way on the particle dynamics in the thinning thread. Here we focus on the very dilute regime where the filament contains only isolated beads to identify the physical mechanisms leading to the pronounced acceleration of the filament thinning observed. This accelerated regime is characterized by an asymmetric shape of the filament with an enhanced curvature that depends on the size and the spatial distribution of the particles within the capillary thread.

Prolonged sitting and markers of cardiometabolic disease risk in children and youth: a randomized crossover study.

PubMed

Saunders, Travis J; Chaput, Jean-Philippe; Goldfield, Gary S; Colley, Rachel C; Kenny, Glen P; Doucet, Eric; Tremblay, Mark S

2013-10-01

Recent evidence suggests that short bouts of uninterrupted sedentary behavior reduce insulin sensitivity and glucose tolerance while increasing triglyceride levels in both healthy and overweight/obese adults. To date no study has examined the acute impact of uninterrupted sitting in children and youth. The objective of the present study was to determine whether 8 h of uninterrupted sitting increases markers of cardiometabolic disease risk in healthy children and youth, in comparison to 8 h of sitting interrupted by light intensity walk breaks or structured physical activity. 11 healthy males and 8 healthy females between the ages of 10 and 14 years experienced 3 conditions in random order: (1) 8 h of uninterrupted sitting (Sedentary); (2) 8 h of sitting interrupted with a 2-min light-intensity walk break every 20 min (Breaks); and (3) 8 h of sitting interrupted with a 2-min light-intensity walk break every 20 min as well as 2×20 min of moderate-intensity physical activity (Breaks+Physical Activity). Insulin, glucose, triglyceride, HDL and LDL cholesterol area under the curve were calculated for each condition. We observed no significant differences in the area under the curve for any marker of cardiometabolic disease risk across the 3 study conditions (all p>0.09). These results suggest that in comparison to interrupted sitting or structured physical activity, a single bout of 8 h of uninterrupted sitting does not result in measurable changes in circulating levels of insulin, glucose, or lipids in healthy children and youth. Copyright © 2013 Elsevier Inc. All rights reserved.

75 FR 80073 - Reasonable Break Time for Nursing Mothers

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-21

... DEPARTMENT OF LABOR Wage and Hour Division RIN 1235-ZA00 Reasonable Break Time for Nursing Mothers... and a place for nursing mothers to express breast milk for one year after their child's birth. The... the break time for nursing mothers law. The break time requirement that is now part of the FLSA is set...

Accelerometer-Derived Pattern of Sedentary and Physical Activity Time in Persons with Mobility Disability: National Health and Nutrition Examination Survey 2003 to 2006.

PubMed

Manns, Patricia; Ezeugwu, Victor; Armijo-Olivo, Susan; Vallance, Jeff; Healy, Genevieve N

2015-07-01

To describe objectively determined sedentary and activity outcomes (volume and pattern) and their associations with cardiometabolic risk biomarkers in individuals with and without mobility disability. Cross-sectional. Population based. Community-dwelling older adults (≥60) living in the United States who were participants in the 2003 to 2004 or 2005 to 2006 National Health and Nutrition Examination Survey. Participants were classified as with or without mobility disability according to responses to self-reported questions about ability to walk, climb stairs, and/or use of ambulatory aids. Accelerometer-derived sedentary and activity variables for volume (time in sedentary (<100 counts per minute (cpm)), very light- (100-759 cpm), light- (760-1,951 cpm), and moderate- to vigorous- (≥1,952 cpm) intensity activity and pattern (number of breaks from sedentary time, duration of sedentary bouts, duration of activity bouts). Survey-weighted regression models, adjusted for age, sex, ethnicity, education, and smoking, were used to examine the associations between pattern of activity and cardiometabolic health risk factors (blood pressure, waist circumference, high-density lipoprotein cholesterol). Of the 2,017 participants, 547 were classified as having a mobility disability. Participants with mobility disability had more sedentary time and less active time than those without. Sedentary bouts were longer and active bouts shorter in those with disability. The total number of sedentary breaks (transitions from sedentary to nonsedentary) differed between groups after adjustment for total sedentary time. Fewer breaks, longer sedentary bouts, and shorter activity bouts were associated with higher average waist circumference regardless of disability status. This study provides rationale for the development and testing of interventions to change the pattern of activity (e.g., include more breaks and longer activity bout durations) in older adults with mobility disability. © 2015, Copyright the Authors Journal compilation © 2015, The American Geriatrics Society.

Part-Time Work and Physical Activity in American High School Students.

PubMed

Van Domelen, Dane R

2015-08-01

To compare physical activity (PA) in American high school students who work part-time with those who do not work. Data were obtained from the National Health and Nutrition Examination Survey 2003 to 2006 (n = 791). Work status was self-reported and PA was measured using accelerometers. In males, adjusted for age, race, and poverty-income ratio, workers averaged greater counts per minute, less sedentary time, and greater moderate-to-vigorous PA compared with nonworkers. In females, workers and nonworkers had similar counts per minute, whereas nonworkers had somewhat greater moderate-to-vigorous PA. There was a work-by-school status interaction on sedentary time (P = 0.021), whereby work was associated with less sedentary time among students not on break from school. In American high school students, work is associated with greater PA in males and a different composition of PA in females.

Decompression Sickness After Air Break in Prebreathe Described with a Survival Model

NASA Technical Reports Server (NTRS)

Conkin, J.; Pilmanis, A. A.

2010-01-01

Data from Brooks City-Base show the decompression sickness (DCS) and venous gas emboli (VGE) consequences of air breaks in a resting 100% O2 prebreathe (PB) prior to a hypobaric exposure. METHODS: DCS and VGE survival times from 95 controls for a 60 min PB prior to 2-hr or 4-hr exposures to 4.37 psia are statistically compared to 3 break in PB conditions: a 10 min (n=40), 20 min (n=40), or 60 min break (n=32) 30 min into the PB followed by 30 min of PB. Ascent rate was 1,524 meters / min and all exposures included light exercise and 4 min of VGE monitoring of heart chambers at 16 min intervals. DCS survival time for combined control and air breaks were described with an accelerated log logistic model where exponential N2 washin during air break was described with a 10 min half-time and washout during PB with a 60 min half-time. RESULTS: There was no difference in VGE or DCS survival times among 3 different air breaks, or when air breaks were compared to control VGE times. However, 10, 20, and 60 min air breaks had significantly earlier survival times compared to control DCS times, certainly early in the exposures. CONCLUSION: Air breaks of 10, 20, and 60 min after 30 min of a 60 min PB reduced DCS survival time. The survival model combined discrete comparisons into a global description mechanistically linked to asymmetrical N2 washin and washout kinetics based on inspired pN2. Our unvalidated regression is used to compute additional PB time needed to compensate for an air break in PB within the range of tested conditions.

Modeling the safety impacts of driving hours and rest breaks on truck drivers considering time-dependent covariates.

PubMed

Chen, Chen; Xie, Yuanchang

2014-12-01

Driving hours and rest breaks are closely related to driver fatigue, which is a major contributor to truck crashes. This study investigates the effects of driving hours and rest breaks on commercial truck driver safety. A discrete-time logistic regression model is used to evaluate the crash odds ratios of driving hours and rest breaks. Driving time is divided into 11 one hour intervals. These intervals and rest breaks are modeled as dummy variables. In addition, a Cox proportional hazards regression model with time-dependent covariates is used to assess the transient effects of rest breaks, which consists of a fixed effect and a variable effect. Data collected from two national truckload carriers in 2009 and 2010 are used. The discrete-time logistic regression result indicates that only the crash odds ratio of the 11th driving hour is statistically significant. Taking one, two, and three rest breaks can reduce drivers' crash odds by 68%, 83%, and 85%, respectively, compared to drivers who did not take any rest breaks. The Cox regression result shows clear transient effects for rest breaks. It also suggests that drivers may need some time to adjust themselves to normal driving tasks after a rest break. Overall, the third rest break's safety benefit is very limited based on the results of both models. The findings of this research can help policy makers better understand the impact of driving time and rest breaks and develop more effective rules to improve commercial truck safety. Copyright © 2014 National Safety Council and Elsevier Ltd. All rights reserved.

How Does Definition of Minimum Break Length Affect Objective Measures of Sitting Outcomes Among Office Workers?

PubMed

Kloster, Stine; Danquah, Ida Høgstedt; Holtermann, Andreas; Aadahl, Mette; Tolstrup, Janne Schurmann

2017-01-01

Harmful health effects associated with sedentary behavior may be attenuated by breaking up long periods of sitting by standing or walking. However, studies assess interruptions in sitting time differently, making comparisons between studies difficult. It has not previously been described how the definition of minimum break duration affects sitting outcomes. Therefore, the aim was to address how definitions of break length affect total sitting time, number of sit-to-stand transitions, prolonged sitting periods and time accumulated in prolonged sitting periods among office workers. Data were collected from 317 office workers. Thigh position was assessed with an ActiGraph GT3X+ fixed on the right thigh. Data were exported with varying bout length of breaks. Afterward, sitting outcomes were calculated for the respective break lengths. Absolute numbers of sit-to-stand transitions decreased, and number of prolonged sitting periods and total time accumulated in prolonged sitting periods increased, with increasing minimum break length. Total sitting time was not influenced by varying break length. The definition of minimum break length influenced the sitting outcomes with the exception of total sitting time. A standard definition of break length is needed for comparison and interpretation of studies in the evolving research field of sedentary behavior.

Sensitivity cycling in physically dormant seeds of the Neotropical tree Senna multijuga (Fabaceae).

PubMed

Rodrigues-Junior, A G; Baskin, C C; Baskin, J M; Garcia, Q S

2018-03-23

Cycling of sensitivity to physical dormancy (PY) break has been documented in herbaceous species. However, it has not been reported in tree seeds, nor has the effect of seed size on sensitivity to PY-breaking been evaluated in any species. Thus, the aims of this study were to investigate how PY is broken in seeds of the tropical legume tree Senna multijuga, if seeds exhibit sensitivity cycling and if seed size affects induction into sensitivity. Dormancy and germination were evaluated in intact and scarified seeds from two collections of S. multijuga. The effects of temperature, moisture and seed size on induction of sensitivity to dormancy-breaking were assessed, and seasonal changes in germination and persistence of buried seeds were determined. Reversal of sensitivity was also investigated. Fresh seeds were insensitive to dormancy break at wet-high temperatures, and an increase in sensitivity occurred in buried seeds after they experienced low temperatures during winter (dry season). Temperatures ≤20 °C increased sensitivity, whereas temperatures ≥30 °C decreased it regardless of moisture conditions. Dormancy was broken in sensitive seeds by incubating them at 35 °C. Sensitivity could be reversed, and large seeds were more sensitive than small seeds to sensitivity induction. Seeds of S. multijuga exhibit sensitivity cycling to PY-breaking. Seeds become sensitive during winter and can germinate with the onset of the spring-summer rainy season in Brazil. Small seeds are slower to become sensitive than large ones, and this may be a mechanism by which germination is spread over time. Sensitive seeds that fail to germinate become insensitive during exposure to drought during summer. This is the first report of sensitivity cycling in a tree species. © 2018 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Physical Education and Physical Activity: Results from the School Health Policies and Programs Study 2006

ERIC Educational Resources Information Center

Lee, Sarah M.; Burgeson, Charlene R.; Fulton, Janet E.; Spain, Christine G.

2007-01-01

Background: Comprehensive school-based physical activity programs consist of physical education and other physical activity opportunities including recess and other physical activity breaks, intramurals, interscholastic sports, and walk and bike to school initiatives. This article describes the characteristics of school physical education and…

Direct observation of ultrafast-electron-transfer reactions unravels high effectiveness of reductive DNA damage

PubMed Central

Nguyen, Jenny; Ma, Yuhan; Luo, Ting; Bristow, Robert G.; Jaffray, David A.; Lu, Qing-Bin

2011-01-01

Both water and electron-transfer reactions play important roles in chemistry, physics, biology, and the environment. Oxidative DNA damage is a well-known mechanism, whereas the relative role of reductive DNA damage is unknown. The prehydrated electron (), a novel species of electrons in water, is a fascinating species due to its fundamental importance in chemistry, biology, and the environment. is an ideal agent to observe reductive DNA damage. Here, we report both the first in situ femtosecond time-resolved laser spectroscopy measurements of ultrafast-electron-transfer (UET) reactions of with various scavengers (KNO3, isopropanol, and dimethyl sulfoxide) and the first gel electrophoresis measurements of DNA strand breaks induced by and OH• radicals co-produced by two-UV-photon photolysis of water. We strikingly found that the yield of reductive DNA strand breaks induced by each is twice the yield of oxidative DNA strand breaks induced by each OH• radical. Our results not only unravel the long-standing mystery about the relative role of radicals in inducing DNA damage under ionizing radiation, but also challenge the conventional notion that oxidative damage is the main pathway for DNA damage. The results also show the potential of femtomedicine as a new transdisciplinary frontier and the broad significance of UET reactions of in many processes in chemistry, physics, biology, and the environment. PMID:21730183

The highest-ranking rooster has priority to announce the break of dawn

PubMed Central

Shimmura, Tsuyoshi; Ohashi, Shosei; Yoshimura, Takashi

2015-01-01

The “cock-a-doodle-doo” crowing of roosters, which symbolizes the break of dawn in many cultures, is controlled by the circadian clock. When one rooster announces the break of dawn, others in the vicinity immediately follow. Chickens are highly social animals, and they develop a linear and fixed hierarchy in small groups. We found that when chickens were housed in small groups, the top-ranking rooster determined the timing of predawn crowing. Specifically, the top-ranking rooster always started to crow first, followed by its subordinates, in descending order of social rank. When the top-ranking rooster was physically removed from a group, the second-ranking rooster initiated crowing. The presence of a dominant rooster significantly reduced the number of predawn crows in subordinates. However, the number of crows induced by external stimuli was independent of social rank, confirming that subordinates have the ability to crow. Although the timing of subordinates’ predawn crowing was strongly dependent on that of the top-ranking rooster, free-running periods of body temperature rhythms differed among individuals, and crowing rhythm did not entrain to a crowing sound stimulus. These results indicate that in a group situation, the top-ranking rooster has priority to announce the break of dawn, and that subordinate roosters are patient enough to wait for the top-ranking rooster’s first crow every morning and thus compromise their circadian clock for social reasons. PMID:26203594

Exploring the Surface Brightness Breaks and Star Formation in Disk Galaxies

NASA Astrophysics Data System (ADS)

Malko, Bradley Ann; Hunter, Deidre Ann

2018-06-01

Stellar surface brightness profiles of both spirals and dwarf irregular galaxies often show breaks in which the exponential fall-off abruptly changes slope. Most often the profile is down-bending (Type II) in the outer disk, but sometimes it is up-bending (Type III). Stellar disks extend a long ways beyond the profile breaks, but we do not understand what happens physically at the breaks. To explore this we are examining the star formation activity, as traced with FUV emission, interior to the break compared to that exterior to the break in both dwarf irregulars and spiral galaxies. We present the results for the spiral galaxy NGC 2500 and compare it to the LITTLE THINGS dwarf irregular galaxies.

Roughness analysis of grade breaks at intersections : final report.

DOT National Transportation Integrated Search

1993-03-01

A method to analyze the roughness of grade breaks at highway intersections is proposed. Although there are a variety of instruments to physically measure the road roughness, there are no known methodologies to analyze profile roughness during the des...

Indicator saturation: a novel approach to detect multiple breaks in geodetic time series.

NASA Astrophysics Data System (ADS)

Jackson, L. P.; Pretis, F.; Williams, S. D. P.

2016-12-01

Geodetic time series can record long term trends, quasi-periodic signals at a variety of time scales from days to decades, and sudden breaks due to natural or anthropogenic causes. The causes of breaks range from instrument replacement to earthquakes to unknown (i.e. no attributable cause). Furthermore, breaks can be permanent or short-lived and range at least two orders of magnitude in size (mm to 100's mm). To account for this range of possible signal-characteristics requires a flexible time series method that can distinguish between true and false breaks, outliers and time-varying trends. One such method, Indicator Saturation (IS) comes from the field of econometrics where analysing stochastic signals in these terms is a common problem. The IS approach differs from alternative break detection methods by considering every point in the time series as a break until it is demonstrated statistically that it is not. A linear model is constructed with a break function at every point in time, and all but statistically significant breaks are removed through a general-to-specific model selection algorithm for more variables than observations. The IS method is flexible because it allows multiple breaks of different forms (e.g. impulses, shifts in the mean, and changing trends) to be detected, while simultaneously modelling any underlying variation driven by additional covariates. We apply the IS method to identify breaks in a suite of synthetic GPS time series used for the Detection of Offsets in GPS Experiments (DOGEX). We optimise the method to maximise the ratio of true-positive to false-positive detections, which improves estimates of errors in the long term rates of land motion currently required by the GPS community.

Developing model-making and model-breaking skills using direct measurement video-based activities

NASA Astrophysics Data System (ADS)

Vonk, Matthew; Bohacek, Peter; Militello, Cheryl; Iverson, Ellen

2017-12-01

This study focuses on student development of two important laboratory skills in the context of introductory college-level physics. The first skill, which we call model making, is the ability to analyze a phenomenon in a way that produces a quantitative multimodal model. The second skill, which we call model breaking, is the ability to critically evaluate if the behavior of a system is consistent with a given model. This study involved 116 introductory physics students in four different sections, each taught by a different instructor. All of the students within a given class section participated in the same instruction (including labs) with the exception of five activities performed throughout the semester. For those five activities, each class section was split into two groups; one group was scaffolded to focus on model-making skills and the other was scaffolded to focus on model-breaking skills. Both conditions involved direct measurement videos. In some cases, students could vary important experimental parameters within the video like mass, frequency, and tension. Data collected at the end of the semester indicate that students in the model-making treatment group significantly outperformed the other group on the model-making skill despite the fact that both groups shared a common physical lab experience. Likewise, the model-breaking treatment group significantly outperformed the other group on the model-breaking skill. This is important because it shows that direct measurement video-based instruction can help students acquire science-process skills, which are critical for scientists, and which are a key part of current science education approaches such as the Next Generation Science Standards and the Advanced Placement Physics 1 course.

Absence of Quantum Time Crystals.

PubMed

Watanabe, Haruki; Oshikawa, Masaki

2015-06-26

In analogy with crystalline solids around us, Wilczek recently proposed the idea of "time crystals" as phases that spontaneously break the continuous time translation into a discrete subgroup. The proposal stimulated further studies and vigorous debates whether it can be realized in a physical system. However, a precise definition of the time crystal is needed to resolve the issue. Here we first present a definition of time crystals based on the time-dependent correlation functions of the order parameter. We then prove a no-go theorem that rules out the possibility of time crystals defined as such, in the ground state or in the canonical ensemble of a general Hamiltonian, which consists of not-too-long-range interactions.

Long-term influence of physical aging processes in epoxy matrix composites

NASA Technical Reports Server (NTRS)

Kong, E. S. W.

1981-01-01

Selected mechanical properties of (plus or minus 45 degree sub 4s) graphite/epoxy composites were found to be affected by sub T sub g annealing. Postcured specimens of Thornel 300 graphite/Narmco 5208 epoxy were sub T sub G annealed at 413 K (140 C) for ca. 10 to the first through 10 to the fifth powers min., with a prior quenching from above T sub g. The ultimate tensile strength, strain-to-break, and toughness of the composite were found to decrease as a function of sub T sub g annealing time. The time-dependent change in properties can be explained on the basis of physical aging which is related to free volume changes in the non-equilibrium glassy state of network epoxies. The results imply possible changes in composite properties with service time.

Defining time crystals via representation theory

NASA Astrophysics Data System (ADS)

Khemani, Vedika; von Keyserlingk, C. W.; Sondhi, S. L.

2017-09-01

Time crystals are proposed states of matter which spontaneously break time translation symmetry. There is no settled definition of such states. We offer a new definition which follows the traditional recipe for Wigner symmetries and order parameters. Supplementing our definition with a few plausible assumptions we find that a) systems with time-independent Hamiltonians should not exhibit time translation symmetry breaking while b) the recently studied π spin glass/Floquet time crystal can be viewed as breaking a global internal symmetry and as breaking time translation symmetry, as befits its two names.

The X-ray Power Density Spectrum of the Seyfert 2 Galaxy NGC 4945: Analysis and Application of the Method of Light Curve Simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mueller, Martin; /SLAC

2010-12-16

The study of the power density spectrum (PDS) of fluctuations in the X-ray flux from active galactic nuclei (AGN) complements spectral studies in giving us a view into the processes operating in accreting compact objects. An important line of investigation is the comparison of the PDS from AGN with those from galactic black hole binaries; a related area of focus is the scaling relation between time scales for the variability and the black hole mass. The PDS of AGN is traditionally modeled using segments of power laws joined together at so-called break frequencies; associations of the break time scales, i.e.,more » the inverses of the break frequencies, with time scales of physical processes thought to operate in these sources are then sought. I analyze the Method of Light Curve Simulations that is commonly used to characterize the PDS in AGN with a view to making the method as sensitive as possible to the shape of the PDS. I identify several weaknesses in the current implementation of the method and propose alternatives that can substitute for some of the key steps in the method. I focus on the complications introduced by uneven sampling in the light curve, the development of a fit statistic that is better matched to the distributions of power in the PDS, and the statistical evaluation of the fit between the observed data and the model for the PDS. Using archival data on one AGN, NGC 3516, I validate my changes against previously reported results. I also report new results on the PDS in NGC 4945, a Seyfert 2 galaxy with a well-determined black hole mass. This source provides an opportunity to investigate whether the PDS of Seyfert 1 and Seyfert 2 galaxies differ. It is also an attractive object for placement on the black hole mass-break time scale relation. Unfortunately, with the available data on NGC 4945, significant uncertainties on the break frequency in its PDS remain.« less

Evaluation of the UP4FUN Intervention: A Cluster Randomized Trial to Reduce and Break Up Sitting Time in European 10-12-Year-Old Children

PubMed Central

Vik, Frøydis N.; Lien, Nanna; Berntsen, Sveinung; De Bourdeaudhuij, Ilse; Grillenberger, Monika; Manios, Yannis; Kovacs, Eva; Chinapaw, Mai J. M.; Brug, Johannes; Bere, Elling

2015-01-01

Background The UP4FUN intervention is a family-involved school-based intervention aiming at reducing and breaking up sitting time at home (with special emphasis on screen time), and breaking up sitting time in school among 10–12 year olds in Europe. The purpose of the present paper was to evaluate its short term effects. Methodology/Principal Findings A total of 3147 pupils from Belgium, Germany, Greece, Hungary and Norway participated in a school-randomized controlled trial. The intervention included 1–2 school lessons per week for a period of six weeks, along with assignments for the children and their parents. Screen time and breaking up sitting time were registered by self-report and total sedentary time and breaking up sitting time by accelerometry. The effect of the intervention on these behaviors was evaluated by multilevel regression analyses. All analyses were adjusted for baseline values and gender. Significance level was p≤0.01. No significant intervention effects were observed, neither for self-reported TV/DVD or computer/game console time, nor for accelerometer-assessed total sedentary time and number of breaks in sitting time. The intervention group, however, reported more positive attitudes towards (β = 0.25 (95% CI 0.11, 0.38)) and preferences/liking for (β = 0.20 (95% CI 0.08, 0.32)) breaking up sitting time than the control group. Conclusions/Significance No significant intervention effect on self-reported screen time or accelerometer-assessed sedentary time or breaks in sitting time was observed, but positive effects on beliefs regarding breaking up sitting time were found in favor of the intervention group. Overall, these results do not warrant wider dissemination of the present UP4FUN intervention. Trial Registration International Standard Randomized Controlled Trial Number Registry ISRCTN34562078 PMID:25826704

The effect of a wearable device prompting high school students aged 17-18 years to break up periods of prolonged sitting in class.

PubMed

Frank, Hanna A; Jacobs, Karen; McLoone, Hugh

2017-01-01

Increasingly, evidence shows that prolonged sedentary behavior factors into the health equation on its own, unrelated to weight and periods of intense exercise. In schools, students are required to sit for long periods of time. To investigate whether reminders (via a wearable device) to change posture, can change students' behavior and impact their subjective wellbeing. Ten students of ages 17 to 18 years at a public high school in Bellevue, Washington, USA. To monitor students' behaviors, specially designed wearable devices recorded periods of sitting, standing and moving of participants throughout the school day for one week. During the second week of the study session, reminders were given via the devices providing vibration feedback after 20 minutes of uninterrupted sitting. Subjective wellbeing was evaluated through a daily questionnaire. The reminders given by the devices were effective in changing students' behavior. Students took significantly more breaks from sitting during the week with reminders. However, changes in subjective well-being were inconclusive. The reminders were effective in changing students' behavior, demonstrating that behavior can be changed through individual feedback. Further study is required to explore benefits of such breaks on students' subjective wellbeing, but other studies suggest that such breaks improve their physical health.

Live cell imaging combined with high-energy single-ion microbeam

NASA Astrophysics Data System (ADS)

Guo, Na; Du, Guanghua; Liu, Wenjing; Guo, Jinlong; Wu, Ruqun; Chen, Hao; Wei, Junzhe

2016-03-01

DNA strand breaks can lead to cell carcinogenesis or cell death if not repaired rapidly and efficiently. An online live cell imaging system was established at the high energy microbeam facility at the Institute of Modern Physics to study early and fast cellular response to DNA damage after high linear energy transfer ion radiation. The HT1080 cells expressing XRCC1-RFP were irradiated with single high energy nickel ions, and time-lapse images of the irradiated cells were obtained online. The live cell imaging analysis shows that strand-break repair protein XRCC1 was recruited to the ion hit position within 20 s in the cells and formed bright foci in the cell nucleus. The fast recruitment of XRCC1 at the ion hits reached a maximum at about 200 s post-irradiation and then was followed by a slower release into the nucleoplasm. The measured dual-exponential kinetics of XRCC1 protein are consistent with the proposed consecutive reaction model, and the measurements obtained that the reaction rate constant of the XRCC1 recruitment to DNA strand break is 1.2 × 10-3 s-1 and the reaction rate constant of the XRCC1 release from the break-XRCC1 complex is 1.2 × 10-2 s-1.

Investigation on thermal oxidative aging of nitrile rubber (NBR) O-rings under compression stress

NASA Astrophysics Data System (ADS)

Liu, X. R.; Zhang, W. F.; Lou, W. T.; Huang, Y. X.; Dai, W.

2017-11-01

The degradation behaviors of nitrile rubber O-rings exposure to air under compression were investigated at three elevated temperatures. The physical and mechanical properties of the aging samples before and after exposure at selected time were studied by measuring weight loss, tensile strength and elongation at break. The Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and fracture morphology were used to reveal the microstructural changes of the aging samples. The results indicate that the weight decreased with exposure time and temperature. Based on the results of the crosslinking density, the crosslinking predominates during the most of aging process. The significant changes in tensile strength and elongation at break also indicate the severe degradation in air. The fracture morphology results show that the fracture surface after 64 days of exposure to air turns rough and present defects. The ATR-FTIR results demonstrate that the hydroxyl groups were formed for the samples aged in air.

Energy curable compositions having improved cure speeds

DOEpatents

Halm, L.W.

1993-05-18

The composition and method provide improved physical properties and cure speed of polyurethane precursors, with or without free radical polymerizable monomers or oligomers present, by use of a two component catalyst system. The resin blend can be activated with a latent organometallic catalyst combined with an organic peroxide which can be a hydroperoxide or an acyl peroxide to decrease the cure time while increasing the break energy and tangent modulus of the system.

Energy curable compositions having improved cure speeds

DOEpatents

Halm, Leo W.

1993-01-01

A composition and method provide improved physical properties and cure speed of polyurethane precursors, with or without free radical polymerizable monomers or oligomers present, by use of a two component catalyst system. The resin blend can be activated with a latent organometallic catalyst combined with an organic peroxide which can be a hydroperoxide or an acyl peroxide to decrease the cure time while increasing the break energy and tangent modulus of the system.

Baryon currents in QCD with compact dimensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lucini, B.; Patella, A.; Istituto Nazionale Fisica Nucleare Sezione di Pisa, Largo Pontecorvo 3, 56126 Pisa

2007-06-15

On a compact space with nontrivial cycles, for sufficiently small values of the radii of the compact dimensions, SU(N) gauge theories coupled with fermions in the fundamental representation spontaneously break charge conjugation, time reversal, and parity. We show at one loop in perturbation theory that a physical signature for this phenomenon is a nonzero baryonic current wrapping around the compact directions. The persistence of this current beyond the perturbative regime is checked by lattice simulations.

Timing During Interruptions in Timing

ERIC Educational Resources Information Center

Fortin, Claudette; Bedard, Marie-Claude; Champagne, Julie

2005-01-01

Duration and location of breaks in time interval production were manipulated in various conditions of stimulus presentation (Experiments 1-4). Produced intervals shortened and then stabilized as break duration lengthened, suggesting that participants used the break as a preparatory period to restart timing as quickly as possible at the end of the…

Motivation and intention to integrate physical activity into daily school life: the JAM World Record event.

PubMed

Vazou, Spyridoula; Vlachopoulos, Symeon P

2014-11-01

Research on the motivation of stakeholders to integrate physical activity into daily school life is limited. The purpose was to examine the motivation of stakeholders to participate in a world record physical activity event and whether motivation was associated with future intention to use activity breaks during the daily school life and future participation in a similar event. After the 2012 JAM (Just-a-Minute) World Record event, 686 adults (591 women; 76.1% participated for children <10 years) completed measures of motivational regulations and future intention to (a) use the activity breaks and (b) participate in the event. High intrinsic motivation and low extrinsic motivation and amotivation for participation in the next event were reported. Hierarchical regression analysis, controlling for age, gender, and occupation, showed that intrinsic forms of motivation positively predicted, whereas amotivation negatively predicted, future intention to participate in the event and use the activity breaks. Multivariate analyses of variance revealed that school-related participants were more intrinsically motivated and intended to use the activity breaks and repeat the event more than those who were not affiliated with a school. Nonschool participants reported higher extrinsic motivation and amotivation than school-related participants. © 2014 Society for Public Health Education.

Selection of optimal conditions for preparation of emulsified fuel fluids

NASA Astrophysics Data System (ADS)

Ivanov, V. A.; Berg, V. I.; Frolov, M. D.

2018-05-01

The aim of the article is to derive the optimal concept of physical and chemical effects, and its application to the production of water-fuel emulsions. The authors set a research task to attempt to estimate the influence of the surfactant concentration on such indicator as the time before the beginning of emulsion breaking. The analysis, based on experimental data, showed that an increase in the concentration of sodium lauryl sulfate is expedient to a certain point, corresponding to 0.05% of the total mass fraction. The main advantage of the model is a rational combination of methods of physical and chemical treatment used in the production of emulsions.

Impact of an 8-Month Trial Using Height-Adjustable Desks on Children’s Classroom Sitting Patterns and Markers of Cardio-Metabolic and Musculoskeletal Health

PubMed Central

Contardo Ayala, Ana María; Salmon, Jo; Timperio, Anna; Sudholz, Bronwyn; Ridgers, Nicola D.; Sethi, Parneet; Dunstan, David W.

2016-01-01

During school hours, children can sit for prolonged and unbroken periods of time. This study investigated the impact of an 8-month classroom-based intervention focusing on reducing and breaking-up sitting time on children’s cardio-metabolic risk factors (i.e., body mass index, waist circumference, blood pressure) and perceptions of musculoskeletal discomfort. Two Year-6 classes (24 students per class) in one primary school were assigned to either an intervention or control classroom. The intervention classroom was equipped with height-adjustable desks and the teacher was instructed in the delivery of pedagogical strategies to reduce and break-up sitting in class. The control classroom followed standard practice using traditional furniture. At baseline, and after 8-months, time spent sitting, standing, stepping, and sitting-bouts (occasions of continuous sitting) as well as the frequency of sit-to-stand transitions were obtained from activPAL inclinometers and the time spent in light-intensity physical activity was obtained from ActiGraph accelerometers. Demographics and musculoskeletal characteristics were obtained from a self-report survey. Hierarchical linear mixed models found that during class-time, children’s overall time spent sitting in long bouts (>10 min) were lower and the number of sit-to-stand transitions were higher in the intervention group compared to the control group, while no changes were observed for musculoskeletal pain/discomfort. No significant intervention effects were found for the anthropometrics measures and blood pressure. Height-adjustable desks and pedagogical strategies to reduce/break-up sitting can positively modify classroom sitting patterns in children. Longer interventions, larger and varied sample size may be needed to show health impacts; however, these desks did not increase musculoskeletal pain/discomfort. PMID:27973414

Effect of a 12-Week Summer Break on School Day Physical Activity and Health-Related Fitness in Low-Income Children from CSPAP Schools

PubMed Central

2017-01-01

Background. The purpose of this study was to examine the effect of a 12-week summer break on school day physical activity and health-related fitness (HRF) in children from schools receiving a Comprehensive School Physical Activity Program (CSPAP). Methods. Participants were school-aged children (N = 1,232; 624 girls and 608 boys; mean age = 9.5 ± 1.8 years) recruited from three low-income schools receiving a CSPAP. Physical activity and HRF levels were collected during the end of spring semester 2015 and again during the beginning of fall semester 2015. Physical activity was assessed using the Yamax DigiWalker CW600 pedometer. HRF measures consisted of body mass index (BMI) and the Progressive Aerobic Cardiovascular Endurance Run (PACER). Results. Results from a doubly MANCOVA analysis indicated that pedometer step counts decreased from 4,929 steps in the spring to 4,445 steps in the fall (mean difference = 484 steps; P < 0.001; Cohen's d = 0.30) and PACER laps decreased from 31.2 laps in the spring to 25.8 laps in the fall (mean difference = 5.4 laps; P < 0.001; Cohen's d = 0.33). Conclusions. Children from schools receiving a CSPAP intervention had lower levels of school day physical activity and cardiorespiratory endurance following a 12-week summer break. PMID:28377791

Effect of a 12-Week Summer Break on School Day Physical Activity and Health-Related Fitness in Low-Income Children from CSPAP Schools.

PubMed

Fu, You; Brusseau, Timothy A; Hannon, James C; Burns, Ryan D

2017-01-01

Background . The purpose of this study was to examine the effect of a 12-week summer break on school day physical activity and health-related fitness (HRF) in children from schools receiving a Comprehensive School Physical Activity Program (CSPAP). Methods . Participants were school-aged children ( N = 1,232; 624 girls and 608 boys; mean age = 9.5 ± 1.8 years) recruited from three low-income schools receiving a CSPAP. Physical activity and HRF levels were collected during the end of spring semester 2015 and again during the beginning of fall semester 2015. Physical activity was assessed using the Yamax DigiWalker CW600 pedometer. HRF measures consisted of body mass index (BMI) and the Progressive Aerobic Cardiovascular Endurance Run (PACER). Results . Results from a doubly MANCOVA analysis indicated that pedometer step counts decreased from 4,929 steps in the spring to 4,445 steps in the fall (mean difference = 484 steps; P < 0.001; Cohen's d = 0.30) and PACER laps decreased from 31.2 laps in the spring to 25.8 laps in the fall (mean difference = 5.4 laps; P < 0.001; Cohen's d = 0.33). Conclusions . Children from schools receiving a CSPAP intervention had lower levels of school day physical activity and cardiorespiratory endurance following a 12-week summer break.

The time-of-day that breaks occur between consecutive duty periods affects the sleep strategies used by shiftworkers.

PubMed

Roach, Gregory D; Dawson, Drew; Reid, Kathryn J; Darwent, David; Sargent, Charli

The aim of this study was to examine the sleep strategies used in breaks between consecutive shifts. For two weeks, 253 shiftworkers collected data regarding the timing of all shifts and sleeps. The final dataset included 395 between-shift breaks that had a standard duration (i.e. ~16 h). If a break included an entire night, participants had a single sleep on 80-93% of occasions, but if a break occurred predominantly during the daytime, participants had more than one sleep on 41-50% of occasions. These data indicate that the sleep strategy employed is influenced by the time-of-day that a break occurs.

Survey of Physical Activity in Elementary School Classrooms in the State of Virginia

ERIC Educational Resources Information Center

Elmakis, Gail Smith

2010-01-01

Elementary school age children engage in levels of physical activity that are well below recommended guidelines. It has been suggested that classroom teachers can assist in remedying the problem by providing physical activity breaks and physical activity embedded in instruction. This study utilized the instrument, Physical Activity in the…

Technical match characteristics and influence of body anthropometry on playing performance in male elite team handball.

PubMed

Michalsik, Lars Bojsen; Madsen, Klavs; Aagaard, Per

2015-02-01

Modern team handball match-play imposes substantial physical and technical demands on elite players. However, only limited knowledge seems to exist about the specific working requirements in elite team handball. Thus, the purpose of this study was to examine the physical demands imposed on male elite team handball players in relation to playing position and body anthropometry. Based on continuous video recording of individual players during elite team handball match-play (62 tournament games, ∼4 players per game), computerized technical match analysis was performed in male elite team handball players along with anthropometric measurements over a 6 season time span. Technical match activities were distributed in 6 major types of playing actions (shots, breakthroughs, fast breaks, tackles, technical errors, and defense errors) and further divided into various subcategories (e.g., hard or light tackles, type of shot, claspings, screenings, and blockings). Players showed 36.9 ± 13.1 (group mean ± SD) high-intense technical playing actions per match with a mean total effective playing time of 53.85 ± 5.87 minutes. In offense, each player performed 6.0 ± 5.2 fast breaks, received 34.5 ± 21.3 tackles in total, and performed in defense 3.7 ± 3.5 blockings, 3.9 ± 3.0 claspings, and 5.8 ± 3.6 hard tackles. Wing players (84.5 ± 5.8 kg, 184.9 ± 5.7 cm) were less heavy and smaller (p < 0.001) than backcourt players (94.7 ± 7.1 kg, 191.9 ± 5.4 cm) and pivots (99.4 ± 6.2 kg, 194.8 ± 3.6 cm). In conclusion, modern male elite team handball match-play is characterized by a high number of short-term, high-intense intermittent technical playing actions. Indications of technical fatigue were observed. Physical demands differed between playing positions with wing players performing more fast breaks and less physical confrontations with opponent players than backcourt players and pivots. Body anthropometry seemed to have an important influence on playing performance because it is highly related to playing positions. The present observations suggest that male elite team handball players should implement more position-specific training regimens, while also focusing on anaerobic training and strength training.

Self-averaging and weak ergodicity breaking of diffusion in heterogeneous media

NASA Astrophysics Data System (ADS)

Russian, Anna; Dentz, Marco; Gouze, Philippe

2017-08-01

Diffusion in natural and engineered media is quantified in terms of stochastic models for the heterogeneity-induced fluctuations of particle motion. However, fundamental properties such as ergodicity and self-averaging and their dependence on the disorder distribution are often not known. Here, we investigate these questions for diffusion in quenched disordered media characterized by spatially varying retardation properties, which account for particle retention due to physical or chemical interactions with the medium. We link self-averaging and ergodicity to the disorder sampling efficiency Rn, which quantifies the number of disorder realizations a noise ensemble may sample in a single disorder realization. Diffusion for disorder scenarios characterized by a finite mean transition time is ergodic and self-averaging for any dimension. The strength of the sample to sample fluctuations decreases with increasing spatial dimension. For an infinite mean transition time, particle motion is weakly ergodicity breaking in any dimension because single particles cannot sample the heterogeneity spectrum in finite time. However, even though the noise ensemble is not representative of the single-particle time statistics, subdiffusive motion in q ≥2 dimensions is self-averaging, which means that the noise ensemble in a single realization samples a representative part of the heterogeneity spectrum.

Proceedings of the workshop on physics at current accelerators and supercolliders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hewett, J L; White, A R; Zeppenfeld, D

1993-06-02

This report contains papers from the workshop on SSC physics. The topics of these papers include: electroweak physics; electroweak symmetry breaking; heavy flavors; searches for new phenomena; strong interactions and full acceptance physics; and event simulation. These paper have been cataloged separately on the data base.

Semester and Event-Specific Motives for Alcohol Use During Spring Break: Associated Protective Strategies and Negative Consequences

PubMed Central

Patrick, Megan E.; Lewis, Melissa A.; Lee, Christine M.; Maggs, Jennifer L.

2012-01-01

Motives surrounding alcohol use behavior are important for understanding college student drinking. However, no previous research has addressed how motives for and against drinking during specific events associated with high-risk drinking, such as Spring Break, may differ from motives for and against drinking during the regular semester. Further, we examine the extent to which semester and Spring Break motives are associated with alcohol use, protective behavioral strategies (PBS), and consequences. Participants were college students (N = 261; 55% women) who provided data both immediately prior to (Wave 1) and after (Wave 2) Spring Break. Fun/Social motives for drinking were greater for Spring Break, and Driving motives against drinking were lower for Spring Break, compared to semester drinking. Relax and Image motives for drinking and Physical/Behavioral motives for not drinking during Spring Break did not differ from semester motives. Spring Break motives for and against drinking were associated with total drinks, maximum drinks, PBS, and experienced negative consequences during Spring Break. Students’ specific motives regarding drinking during Spring Break predict high-risk drinking and may be utilized in creating salient event-specific interventions. PMID:23384451

Target effect on the kinematics of Taekwondo Roundhouse Kick - is the presence of a physical target a stimulus, influencing muscle-power generation?

PubMed

Wąsik, Jacek; Shan, Gongbing

2015-01-01

Taekwondo is famous for its powerful kicking techniques and the roundhouse kick is the most frequently used one. In earlier literature, the influence of a physical target (exiting or not) on kicking power generation has not been given much attention. Therefore, the aim of this study was to investigate the kinematics of roundhouse kick execution and its factors related to power generation. 6 ITF taekwondo practitioners voluntarily participated in this study. They were asked to perform kicks with and without a physical target. The first kick aimed at breaking a board while the second one was a kick into the air. A Smart-D motion capture system (BTS S.p.A., Italy) was used to quantitatively determine their kinematic characteristics during each kick. The main findings showed that kicks aiming at a breaking board were significantly slower than kicks without a physical target (maximal kick-foot velocities were 10.61 ± 0.86 m/s and 14.61 ± 0.67 m/s, respectively, p < 0.01), but the kicking time of the former was shorter (0.58 ± 0.01 s and 0.67 ± 0.01, respectively, p < 0.01). The results suggest that a physical target will negatively influence the kick-foot velocity, which is not necessarily a disadvantage for creating a high quality kick. Possible motor control mechanisms are discussed for the phenomenon. The study made it clear: trainings with and without physical targets would develop different motor control patterns. More studies are needed for identifying the effectiveness of different controls and efficiencies of their training.

Cracks dynamics under tensional stress - a DEM approach

NASA Astrophysics Data System (ADS)

Debski, Wojciech; Klejment, Piotr; Kosmala, Alicja; Foltyn, Natalia; Szpindler, Maciej

2017-04-01

Breaking and fragmentation of solid materials is an extremely complex process involving scales ranging from an atomic scale (breaking inter-atomic bounds) up to thousands of kilometers in case of catastrophic earthquakes (in energy scale it ranges from single eV up to 1024 J). Such a large scale span of breaking processes opens lot of questions like, for example, scaling of breaking processes, existence of factors controlling final size of broken area, existence of precursors, dynamics of fragmentation, to name a few. The classical approach to study breaking process at seismological scales, i.e., physical processes in earthquake foci, is essentially based on two factors: seismic data (mostly) and the continuum mechanics (including the linear fracture mechanics). Such approach has been gratefully successful in developing kinematic (first) and dynamic (recently) models of seismic rupture and explaining many of earthquake features observed all around the globe. However, such approach will sooner or latter face a limitation due to a limited information content of seismic data and inherit limitations of the fracture mechanics principles. A way of avoiding this expected limitation is turning an attention towards a well established in physics method of computational simulations - a powerful branch of contemporary physics. In this presentation we discuss preliminary results of analysis of fracturing dynamics under external tensional forces using the Discrete Element Method approach. We demonstrate that even under a very simplified tensional conditions, the fragmentation dynamics is a very complex process, including multi-fracturing, spontaneous fracture generation and healing, etc. We also emphasis a role of material heterogeneity on the fragmentation process.

Characteristic Variability Timescales in the Gamma-ray Power Spectra of Blazars

NASA Astrophysics Data System (ADS)

Ryan, James Lee; Siemiginowska, Aneta; Sobolewska, Malgorzata; Grindlay, Jonathan E.

2018-01-01

We study the gamma-ray variability of 13 bright blazars observed with the Fermi Large Area Telescope in the 0.2-300 MeV band over 7.8 years.We find that continuous-time autoregressive moving average (CARMA) models provide adequate fits to the blazar light curves, and using the models we constrain the power spectral density (PSD) of each source.We also perform simulations to test the ability of CARMA modeling to recover the PSDs of artificial light curves with our data quality.Seven sources show evidence for a low-frequency break at an average timescale of ~1 year, with five of these sources showing evidence for an additional high-frequency break at an average timescale of ~7 days.We compare our results to previous studies, and discuss the possible physical interpretations of our results.

Hybrid Eulerian and Lagrangian Simulation of Steep and Breaking Waves and Surface Fluxes in High Winds

DTIC Science & Technology

2012-09-30

Lagrangian methods for free - surface turbulence and wave simulation . In the far field, coupled wind and wave simulations are used to obtain wind...to conserve the mass precisely. When the wave breaks, the flow at the free surface may become very violent, air and water may be highly mixed...fluids free - surface flows that can be used to study the fundamental physics of wave breaking. The research will improve the understanding of air-sea

Time symmetry breaking in Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Mendonça, J. T.; Gammal, A.

2017-09-01

We consider different processes leading to time symmetry breaking in a Bose-Einstein condensate. Our approach provides a global description of time symmetry breaking, based on the equations of a thermal condensate. This includes quenching and expansion of the condensate, the Kibble-Zurek mechanism associated with the creation of vorticity, the dynamical Casimir effect and the formation of time crystals.

Get a Kick Out of Physics.

ERIC Educational Resources Information Center

Hildreth, David P.; Matthews, Catherine E.

1997-01-01

Describes a number of demonstrations for physics that employ techniques of the martial arts to illustrate Newton's second law of motion. Demonstrations focus on the breaking of wooden boards using weights. (DDR)

Order statistics inference for describing topological coupling and mechanical symmetry breaking in multidomain proteins

NASA Astrophysics Data System (ADS)

Kononova, Olga; Jones, Lee; Barsegov, V.

2013-09-01

Cooperativity is a hallmark of proteins, many of which show a modular architecture comprising discrete structural domains. Detecting and describing dynamic couplings between structural regions is difficult in view of the many-body nature of protein-protein interactions. By utilizing the GPU-based computational acceleration, we carried out simulations of the protein forced unfolding for the dimer WW - WW of the all-β-sheet WW domains used as a model multidomain protein. We found that while the physically non-interacting identical protein domains (WW) show nearly symmetric mechanical properties at low tension, reflected, e.g., in the similarity of their distributions of unfolding times, these properties become distinctly different when tension is increased. Moreover, the uncorrelated unfolding transitions at a low pulling force become increasingly more correlated (dependent) at higher forces. Hence, the applied force not only breaks "the mechanical symmetry" but also couples the physically non-interacting protein domains forming a multi-domain protein. We call this effect "the topological coupling." We developed a new theory, inspired by order statistics, to characterize protein-protein interactions in multi-domain proteins. The method utilizes the squared-Gaussian model, but it can also be used in conjunction with other parametric models for the distribution of unfolding times. The formalism can be taken to the single-molecule experimental lab to probe mechanical cooperativity and domain communication in multi-domain proteins.

Time Crystal Behavior of Excited Eigenstates

NASA Astrophysics Data System (ADS)

Syrwid, Andrzej; Zakrzewski, Jakub; Sacha, Krzysztof

2017-12-01

In analogy to spontaneous breaking of continuous space translation symmetry in the process of space crystal formation, it was proposed that spontaneous breaking of continuous time translation symmetry could lead to time crystal formation. In other words, a time-independent system prepared in the energy ground state is expected to reveal periodic motion under infinitely weak perturbation. In the case of the system proposed originally by Wilczek, spontaneous breaking of time translation symmetry cannot be observed if one starts with the ground state. We point out that the symmetry breaking can take place if the system is prepared in an excited eigenstate. The latter can be realized experimentally in ultracold atomic gases. We simulate the process of the spontaneous symmetry breaking due to measurements of particle positions and analyze the lifetime of the resulting symmetry broken state.

Time Crystal Behavior of Excited Eigenstates.

PubMed

Syrwid, Andrzej; Zakrzewski, Jakub; Sacha, Krzysztof

2017-12-22

In analogy to spontaneous breaking of continuous space translation symmetry in the process of space crystal formation, it was proposed that spontaneous breaking of continuous time translation symmetry could lead to time crystal formation. In other words, a time-independent system prepared in the energy ground state is expected to reveal periodic motion under infinitely weak perturbation. In the case of the system proposed originally by Wilczek, spontaneous breaking of time translation symmetry cannot be observed if one starts with the ground state. We point out that the symmetry breaking can take place if the system is prepared in an excited eigenstate. The latter can be realized experimentally in ultracold atomic gases. We simulate the process of the spontaneous symmetry breaking due to measurements of particle positions and analyze the lifetime of the resulting symmetry broken state.

Validity of two wearable monitors to estimate breaks from sedentary time

PubMed Central

Lyden, Kate; Kozey-Keadle, Sarah L.; Staudenmayer, John W.; Freedson, Patty S.

2012-01-01

Investigations employing wearable monitors have begun to examine how sedentary time behaviors influence health. Purpose To demonstrate the utility of a measure of sedentary behavior and to validate the activPAL and ActiGraph GT3X for estimating measures of sedentary behavior: absolute number of breaks and break-rate. Methods Thirteen participants completed two, 10-hour conditions. During the baseline condition, participants performed normal daily activity and during the treatment condition, participants were asked to reduce and break-up their sedentary time. In each condition, participants wore two ActiGraph GT3X monitors and one activPAL. The ActiGraph was tested using the low frequency extension filter (AG-LFE) and the normal filter (AG-Norm). For both ActiGraph monitors two count cut-points to estimate sedentary time were examined: 100 and 150 counts∙min−1. Direct observation served as the criterion measure of total sedentary time, absolute number of breaks from sedentary time and break-rate (number of breaks per sedentary hour [brks.sed-hr−1]). Results Break-rate was the only metric sensitive to changes in behavior between baseline (5.1 [3.3 to 6.8] brks.sed-hr−1) and treatment conditions (7.3 [4.7 to 9.8] brks.sed-hr−1) (mean [95% CI]). The activPAL produced valid estimates of all sedentary behavior measures and was sensitive to changes in break-rate between conditions (baseline: 5.1 [2.8 to 7.1] brks.sed-hr−1, treatment: 8.0 [5.8 to 10.2] brks.sed-hr−1). In general, the AG-LFE and AG-Norm were not accurate in estimating break-rate or absolute number of breaks and were not sensitive to changes between conditions. Conclusion This study demonstrates the utility of expressing breaks from sedentary time as a rate per sedentary hour, a metric specifically relevant to free-living behavior, and provides further evidence that the activPAL is a valid tool to measure components of sedentary behavior in free-living environments. PMID:22648343

Acceptability and feasibility of potential intervention strategies for influencing sedentary time at work: focus group interviews in executives and employees.

PubMed

De Cocker, Katrien; Veldeman, Charlene; De Bacquer, Dirk; Braeckman, Lutgart; Owen, Neville; Cardon, Greet; De Bourdeaudhuij, Ilse

2015-02-18

Occupational sitting can be the largest contributor to overall daily sitting time in white-collar workers. With adverse health effects in adults, intervention strategies to influence sedentary time on a working day are needed. Therefore, the present aim was to examine employees' and executives' reflections on occupational sitting and to examine the potential acceptability and feasibility of intervention strategies to reduce and interrupt sedentary time on a working day. Seven focus groups (four among employees, n = 34; three among executives, n = 21) were conducted in a convenience sample of three different companies in Flanders (Belgium), using a semi-structured questioning route in five themes [personal sitting patterns; intervention strategies during working hours, (lunch) breaks, commuting; and intervention approach]. The audiotaped interviews were verbatim transcribed, followed by a qualitative inductive content analysis in NVivo 10. The majority of participants recognized they spend their working day mostly sitting and associated this mainly with musculoskeletal health problems. Participants suggested a variety of possible strategies, primarily for working hours (standing during phone calls/meetings, PC reminders, increasing bathroom use by drinking more water, active sitting furniture, standing desks, rearranging the office) and (lunch) breaks (physical activity, movement breaks, standing tables). However, several barriers were reported, including productivity concerns, impracticality, awkwardness of standing, and the habitual nature of sitting. Facilitating factors were raising awareness, providing alternatives for simply standing, making some strategies obligatory and workers taking some personal responsibility. There are some strategies targeting sedentary time on a working day that are perceived to be realistic and useful. However several barriers emerged, which future trials and practical initiatives should take into account.

ALICE in the early Universe wonderland

NASA Astrophysics Data System (ADS)

Di Nezza, Pasquale

2012-03-01

In these years the Large Hadron Collider (LHC) at CERN is probing, for the first time, physics at energy scales more than an order of magnitude beyond that of the Standard Model. These experiments explore an energy regime of particle physics where phenomena, such as supersymmetry and Grand Unified Theories, may become relevant. Certainly, the LHC should shed light on the mechanism of electroweak symmetry breaking and may discover the first fundamental scalar particle seen in nature. The collisions of heavy ions (Pb - Pb) will create the same "soup" the early Universe had at the epoch of 10-5 seconds. In general, there is a strong and growing interplay between particle physics and cosmology, in particular in the possible production of mini black holes and dark matter candidates like the lightest neutralino in the MSSM.

Designing physics video hooks for science students

NASA Astrophysics Data System (ADS)

McHugh, M.; McCauley, V.

2016-01-01

This paper offers an insight into the design structure of physics video hooks that were developed by the Science Education Resource design team in the school of education (SOE) in National University of Ireland, Galway (NUI Galway). A hook, is an instructional technique used to stimulate student attention (Hunter 1994, Lemov 2010), interest (Jewett 2013) and engagement (McCrory 2011, Riendeau 2013). The physics video hooks followed a design framework that is illustrated below by breaking down the centre of gravity (COG) hook. Various design principles and elements embedded within the COG hook are presented with examples and the time they occur within the video. The intention of this article is that the design can be replicated and modified to aid teachers and designers in the development of a multitude of classroom based multimedia resources.

Decompression sickness after air break in prebreathe described with a survival model.

PubMed

Conkin, Johnny

2011-06-01

A perception exists in aerospace that a brief interruption in a 100% oxygen prebreathe (PB) by breathing air has a substantial decompression sickness (DCS) consequence. The consequences of an air break during PB on the subsequent hypobaric DCS outcomes were evaluated. The hypothesis was that asymmetrical and not symmetrical nitrogen (N2) kinetics was best to model the distribution of subsequent DCS survival times after PBs that included air breaks. DCS survival times from 95 controls for a 60-min PB prior to 2- or 4-h exposures to 4.37 psia (9144 m; 30,000 ft) were analyzed along with 3 experimental conditions: 10-min air break (N = 40), 20-min air break (N = 40), or 60-min air break (N = 32) 30 min into the PB followed by 30 min of PB. Ascent rate was 1524 m x min(-1) and all 207 exposures included light exercise at 4.37 psia. Various computations of decompression dose were evaluated; either the difference or ratio of P1N2 and P2, where P1N2 was computed tissue N2 pressure to account for the PB and P2 was altitude pressure. Survival times were described with an accelerated log logistic model with asymmetrical N2 kinetics defining P1N2--P2 as best decompression dose. Exponential N2 uptake during the air break was described with a 10-min half time and N2 elimination during PB with a 60-min half time. A simple conclusion about compensation for air break is not possible because the duration and location of a break in a PB is variable. The resulting survival model is used to compute additional PB time to compensate for an air break in PB within the range of tested conditions.

Booster Breaks in the workplace: participants’ perspectives on health-promoting work breaks

PubMed Central

Taylor, Wendell C.; King, Kathryn E.; Shegog, Ross; Paxton, Raheem J.; Evans-Hudnall, Gina L.; Rempel, David M.; Chen, Vincent; Yancey, Antronette K.

2013-01-01

Increasing sedentary work has been associated with greater cardiovascular and metabolic risk, as well as premature mortality. Interrupting the sedentary workday with health-promoting work breaks can counter these negative health effects. To examine the potential sustainability of work-break programs, we assessed the acceptance of these breaks among participants in a Booster Break program. We analyzed qualitative responses from 35 participants across five worksites where one 15-min physical activity break was taken each workday. Two worksites completed a 1-year intervention and three worksites completed a 6-month intervention. Responses to two open-ended questions about the acceptance and feasibility of Booster Breaks were obtained from a survey administered after the intervention. Three themes for benefits and two themes for barriers were identified. The benefit themes were (i) reduced stress and promoted enjoyment, (ii) increased health awareness and facilitated behavior change, and (iii) enhanced workplace social interaction. The barrier themes were the need for (iv) greater variety in Booster Break routines and (v) greater management support. This study provides empirical support for the acceptance and feasibility of Booster Breaks during the workday. Emphasizing the benefits and minimizing the barriers are strategies that can be used to implement Booster Breaks in other workplaces. PMID:23466367

Regulating strain states by using the recovery potential of lunch breaks.

PubMed

Krajewski, Jarek; Wieland, Rainer; Sauerland, Martin

2010-04-01

The aim of the worksite study is to elucidate the strain reducing impact of different forms of spending lunch breaks. With the help of the so-called silent room cabin concept, it was possible to induce a lunch-break relaxation opportunity that provided visual and territorial privacy. To evaluate the proposed effects, 14 call center agents were assigned to either 20 min progressive muscle relaxation (PMR) or small-talk (ST) break groups. We analyzed the data in a controlled trial for a period of 6 months (every 2 months four measurements a day at 12:00, 13:00, 16:00, 20:00) using independent observer and self-report ratings of emotional, mental, motivational, and physical strain. Results indicated that only the PMR break reduced postlunchtime and afternoon strain. Although further intervention research is required, our results suggest that PMR lunch break may sustainable reduce strain states in real worksite settings. Copyright 2010 APA, all rights reserved.

A 30-Minute Physical Education Program Improves Students' Executive Attention

ERIC Educational Resources Information Center

Kubesch, Sabine; Walk, Laura; Spitzer, Manfred; Kammer, Thomas; Lainburg, Alyona; Heim, Rudiger; Hille, Katrin

2009-01-01

Physical activity is not only beneficial to physical health but also to cognitive functions. In particular, executive functions that are closely related to learning achievement can be improved by acute and recurring physical activity. We examined the effects of a single 30-min physical education program in contrast to a 5-min movement break on…

Variability and interaction of some egg physical and eggshell quality attributes during the entire laying hen cycle.

PubMed

Sirri, F; Zampiga, M; Berardinelli, A; Meluzzi, A

2018-05-01

The aim of this study was to investigate the variability and relationships between some egg physical (egg weight, width, length, shape index, and surface area) and eggshell parameters (weight and percentage, thickness, breaking strength, and L*, a*, and b* values) during the entire laying hen cycle. A total of 8,000 eggs was collected every 5 wk, from 30 to 81 wk of hen age (10 samplings of 400 eggs/house), in 2 identical poultry houses equipped with enriched cages. For the statistical analysis, ANOVA, Bivariate Correlation, Principal Component Analysis (PCA), and Hierarchical Cluster Analysis were used. An increase of egg weight, length, and eggshell lightness (L*) associated with a reduction of eggshell percentage, breaking strength, and redness (a*) was observed as the hen aged (P < 0.05). Overall, the coefficients of variation resulted in <5% in width, length, shape index, and egg surface area; from 5 to 10% of egg weight, shell weight, shell percentage, shell thickness, L*, and b*; and >10% of eggshell breaking strength and a*. According to the PCA, the highest changes during the laying cycle are related to egg physical parameters (32%) and to eggshell breaking strength, percentage, and thickness (26%). The egg physical parameters appeared to be strongly correlated to each other, whereas a slight correlation between eggshell breaking strength and color attributes were evidenced (-0.231 and 0.289, respectively, for L* and a*; P < 0.01). Hierarchical cluster analysis, based on principal components of the overall egg attributes, is hereby considered, and evidenced dissimilarities for eggs laid from peak production up for 39 wk of hen age from the eggs laid afterwards. The latter group could also be divided into 2 subgroups, one comprising eggs laid from 44 and 53 wk of hen age and the other from 58 wk to the end. In conclusion, the large dataset created in this study allowed to extrapolate some robust information regarding the variability and correlations of the egg physical and eggshell quality attributes throughout the entire laying hen cycle.

Localized Symmetry Breaking for Tuning Thermal Expansion in ScF 3 Nanoscale Frameworks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Lei; Qin, Feiyu; Sanson, Andrea

The local symmetry, beyond the averaged crystallographic structure, tends to bring unu-sual performances. Negative thermal expansion is a peculiar physical property of solids. Here, we report the delicate design of the localized symmetry breaking to achieve the controllable thermal expansion in ScF3 nano-scale frameworks. Intriguingly, an isotropic zero thermal expansion is concurrently engi-neered by localized symmetry breaking, with a remarkably low coefficient of thermal expansion of about +4.0×10-8/K up to 675K. This mechanism is investigated by the joint analysis of atomic pair dis-tribution function of synchrotron X-ray total scattering and extended X-ray absorption fine structure spectra. A localized rhombohedral distortionmore » presumably plays a critical role in stiffening ScF3 nano-scale frameworks and concomitantly suppressing transverse thermal vibrations of fluorine atoms. This physical scenario is also theoretically corroborated by the extinction of phonon modes with negative Grüneisen parameters in the rhombohedral ScF3. The present work opens an untraditional chemical modification to achieve controllable thermal expansion by breaking local symmetries of materials.« less

Feasibility of Workplace Health Promotion for Restaurant Workers, Seattle, 2012.

PubMed

Allen, Claire L; Hammerback, Kristen; Harris, Jeffrey R; Hannon, Peggy A; Parrish, Amanda T

2015-10-08

Restaurant workers are a large population at high risk for tobacco use, physical inactivity, and influenza. They are difficult to reach with health care interventions and may be more accessible through workplaces, yet few studies have explored the feasibility of workplace health promotion in this population. This study sought to identify barriers and facilitators to promotion of tobacco cessation, physical activity, and influenza vaccination in restaurants. Moderators conducted 7 focus groups, 3 with restaurant owners and managers, 2 with English-speaking workers, and 2 with Spanish-speaking workers. All groups were recorded, and recordings were transcribed and uploaded to qualitative-analysis software. Two researchers coded each transcript independently and analyzed codes and quotations for common themes. Seventy people from the restaurant industry participated. Barriers to workplace health promotion included smoking-break customs, little interest in physical activity outside of work, and misinformation about influenza vaccinations. Facilitators included creating and enforcing equitable break policies and offering free, on-site influenza vaccinations. Spanish-speakers were particularly amenable to vaccination, despite their perceptions of low levels of management support for health promotion overall. Owners required a strong business case to consider investing in long-term prevention for their employees. Tobacco cessation and influenza vaccinations are opportunities for health promotion among restaurant workers, whereas physical activity interventions face greater challenges. Promotion of equitable breaks, limited smoking-break policies, and free, on-site influenza vaccinations could improve health for restaurant workers, who often do not have health insurance. Workplace interventions may be particularly important for Hispanic workers who have additional access barriers.

Feasibility of Workplace Health Promotion for Restaurant Workers, Seattle, 2012

PubMed Central

Hammerback, Kristen; Harris, Jeffrey R.; Hannon, Peggy A.; Parrish, Amanda T.

2015-01-01

Introduction Restaurant workers are a large population at high risk for tobacco use, physical inactivity, and influenza. They are difficult to reach with health care interventions and may be more accessible through workplaces, yet few studies have explored the feasibility of workplace health promotion in this population. This study sought to identify barriers and facilitators to promotion of tobacco cessation, physical activity, and influenza vaccination in restaurants. Methods Moderators conducted 7 focus groups, 3 with restaurant owners and managers, 2 with English-speaking workers, and 2 with Spanish-speaking workers. All groups were recorded, and recordings were transcribed and uploaded to qualitative-analysis software. Two researchers coded each transcript independently and analyzed codes and quotations for common themes. Results Seventy people from the restaurant industry participated. Barriers to workplace health promotion included smoking-break customs, little interest in physical activity outside of work, and misinformation about influenza vaccinations. Facilitators included creating and enforcing equitable break policies and offering free, on-site influenza vaccinations. Spanish-speakers were particularly amenable to vaccination, despite their perceptions of low levels of management support for health promotion overall. Owners required a strong business case to consider investing in long-term prevention for their employees. Conclusion Tobacco cessation and influenza vaccinations are opportunities for health promotion among restaurant workers, whereas physical activity interventions face greater challenges. Promotion of equitable breaks, limited smoking-break policies, and free, on-site influenza vaccinations could improve health for restaurant workers, who often do not have health insurance. Workplace interventions may be particularly important for Hispanic workers who have additional access barriers. PMID:26447549

Mode structure symmetry breaking of energetic particle driven beta-induced Alfvén eigenmode

NASA Astrophysics Data System (ADS)

Lu, Z. X.; Wang, X.; Lauber, Ph.; Zonca, F.

2018-01-01

The mode structure symmetry breaking of energetic particle driven Beta-induced Alfvén Eigenmode (BAE) is studied based on global theory and simulation. The weak coupling formula gives a reasonable estimate of the local eigenvalue compared with global hybrid simulation using XHMGC. The non-perturbative effect of energetic particles on global mode structure symmetry breaking in radial and parallel (along B) directions is demonstrated. With the contribution from energetic particles, two dimensional (radial and poloidal) BAE mode structures with symmetric/asymmetric tails are produced using an analytical model. It is demonstrated that the symmetry breaking in radial and parallel directions is intimately connected. The effects of mode structure symmetry breaking on nonlinear physics, energetic particle transport, and the possible insight for experimental studies are discussed.

Effectiveness of a worksite social & physical environment intervention on need for recovery, physical activity and relaxation; results of a randomized controlled trial.

PubMed

Coffeng, Jennifer K; Boot, Cécile R L; Duijts, Saskia F A; Twisk, Jos W R; van Mechelen, Willem; Hendriksen, Ingrid J M

2014-01-01

To investigate the effectiveness of a worksite social and physical environment intervention on need for recovery (i.e., early symptoms of work-related mental and physical fatigue), physical activity and relaxation. Also, the effectiveness of the separate interventions was investigated. In this 2 × 2 factorial design study, 412 office employees from a financial service provider participated. Participants were allocated to the combined social and physical intervention, to the social intervention only, to the physical intervention only or to the control group. The primary outcome measure was need for recovery. Secondary outcomes were work-related stress (i.e., exhaustion, detachment and relaxation), small breaks, physical activity (i.e., stair climbing, active commuting, sport activities, light/moderate/vigorous physical activity) and sedentary behavior. Outcomes were measured by questionnaires at baseline, 6 and 12 months follow-up. Multilevel analyses were performed to investigate the effects of the three interventions. In all intervention groups, a non-significant reduction was found in need for recovery. In the combined intervention (n = 92), exhaustion and vigorous physical activities decreased significantly, and small breaks at work and active commuting increased significantly compared to the control group. The social intervention (n = 118) showed a significant reduction in exhaustion, sedentary behavior at work and a significant increase in small breaks at work and leisure activities. In the physical intervention (n = 96), stair climbing at work and active commuting significantly increased, and sedentary behavior at work decreased significantly compared to the control group. None of the interventions was effective in improving the need for recovery. It is recommended to implement the social and physical intervention among a population with higher baseline values of need for recovery. Furthermore, the intervention itself could be improved by increasing the intensity of the intervention (for example weekly GMI-sessions), providing physical activity opportunities and exercise schemes, and by more drastic environment interventions (restructuring entire department floor). Nederlands Trial Register NTR2553.

Evolution of record-breaking high and low monthly mean temperatures

NASA Astrophysics Data System (ADS)

Anderson, A. L.; Kostinski, A. B.

2011-12-01

We examine the ratio of record-breaking highs to record-breaking lows with respect to extent of time-series for monthly mean temperatures within the continental United States (1900-2006) and ask the following question. How are record-breaking high and low surface temperatures in the United States affected by time period? We find that the ratio of record-breaking highs to lows in 2006 increases as the time-series extend further into the past. For example: in 2006, the ratio of record-breaking highs to record-breaking lows is ≈ 13 : 1 with 1950 as the first year and ≈ 25 : 1 with 1900 as the first year; both ratios are an order of magnitude greater than 3-σ for stationary simulations. We also find record-breaking events are more sensitive to trends in time-series of monthly averages than time-series of corresponding daily values. When we consider the ratio as it evolves with respect to a fixed start year, we find it is strongly correlated with the ensemble mean. Correlation coefficients are 0.76 and 0.82 for 1900-2006 and 1950-2006 respectively; 3-σ = 0.3 for pairs of uncorrelated stationary time-series. We find similar values for globally distributed time-series: 0.87 and 0.92 for 1900-2006 and 1950-2006 respectively. However, the ratios evolve differently: global ratios increase throughout (1920-2006) while continental United States ratios decrease from about 1940 to 1970. (Based on Anderson and Kostinski (2011), Evolution and distribution of record-breaking high and low monthly mean temperatures. Journal of Applied Meteorology and Climatology. doi: 10.1175/JAMC-D-10-05025.1)

Surf physics

NASA Astrophysics Data System (ADS)

Edge, Ronald

2001-05-01

Just what is happening when a surfer taps into the energy of a breaking wave and rides to shore? It's sport, it's art, it's skill, stamina, and drama. It is also physics — hydrodynamics, wave propagation, kinematics, and dynamics.

Real-time full-field characterization of transient dissipative soliton dynamics in a mode-locked laser

NASA Astrophysics Data System (ADS)

Ryczkowski, P.; Närhi, M.; Billet, C.; Merolla, J.-M.; Genty, G.; Dudley, J. M.

2018-04-01

Dissipative solitons are remarkably localized states of a physical system that arise from the dynamical balance between nonlinearity, dispersion and environmental energy exchange. They are the most universal form of soliton that can exist, and are seen in far-from-equilibrium systems in many fields, including chemistry, biology and physics. There has been particular interest in studying their properties in mode-locked lasers, but experiments have been limited by the inability to track the dynamical soliton evolution in real time. Here, we use simultaneous dispersive Fourier transform and time-lens measurements to completely characterize the spectral and temporal evolution of ultrashort dissipative solitons as their dynamics pass through a transient unstable regime with complex break-up and collisions before stabilization. Further insight is obtained from reconstruction of the soliton amplitude and phase and calculation of the corresponding complex-valued eigenvalue spectrum. These findings show how real-time measurements provide new insights into ultrafast transient dynamics in optics.

A comparison of G2 phase radiation-induced chromatid break kinetics using calyculin-PCC with those obtained using colcemid block.

PubMed

Bryant, Peter E; Mozdarani, Hossein

2007-09-01

To study the possible influence of cell-cycle delay on cells reaching mitosis during conventional radiation-induced chromatid break experiments using colcemid as a blocking agent, we have compared the chromatid break kinetics following a single dose of gamma rays (0.75 Gy) in metaphase CHO cells using calyculin-induced premature chromosome condensation (PCC), with those using colcemid block. Calyculin-induced PCC causes very rapid condensation of G2 cell chromosomes without the need for a cell to progress to mitosis, hence eliminating any effect of cell-cycle checkpoint on chromatid break frequency. We found that the kinetics of the exponential first-order decrease in chromatid breaks with time after irradiation was similar (not significantly different) between the two methods of chromosome condensation. However, use of the calyculin-PCC technique resulted in a slightly increased rate of disappearance of chromatid breaks and thus higher frequencies of breaks at 1.5 and 2.5 h following irradiation. We also report on the effect of the nucleoside analogue ara A on chromatid break kinetics using the two chromosome condensation techniques. Ara A treatment of cells abrogated the decrease in chromatid breaks with time, both using the calyculin-PCC and colcemid methods. We conclude that cell-cycle delay may be a factor determining the absolute frequency of chromatid breaks at various times following irradiation of cells in G2 phase but that the first-order disappearance of chromatid breaks with time and its abrogation by ara A are not significantly influenced by the G2 checkpoint.

Live cell imaging combined with high-energy single-ion microbeam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Na; Du, Guanghua, E-mail: gh-du@impcas.ac.cn; Liu, Wenjing

DNA strand breaks can lead to cell carcinogenesis or cell death if not repaired rapidly and efficiently. An online live cell imaging system was established at the high energy microbeam facility at the Institute of Modern Physics to study early and fast cellular response to DNA damage after high linear energy transfer ion radiation. The HT1080 cells expressing XRCC1-RFP were irradiated with single high energy nickel ions, and time-lapse images of the irradiated cells were obtained online. The live cell imaging analysis shows that strand-break repair protein XRCC1 was recruited to the ion hit position within 20 s in themore » cells and formed bright foci in the cell nucleus. The fast recruitment of XRCC1 at the ion hits reached a maximum at about 200 s post-irradiation and then was followed by a slower release into the nucleoplasm. The measured dual-exponential kinetics of XRCC1 protein are consistent with the proposed consecutive reaction model, and the measurements obtained that the reaction rate constant of the XRCC1 recruitment to DNA strand break is 1.2 × 10{sup −3} s{sup −1} and the reaction rate constant of the XRCC1 release from the break-XRCC1 complex is 1.2 × 10{sup −2} s{sup −1}.« less

Bud break responds more strongly to daytime than night-time temperature under asymmetric experimental warming.

PubMed

Rossi, Sergio; Isabel, Nathalie

2017-01-01

Global warming is diurnally asymmetric, leading to a less cold, rather than warmer, climate. We investigated the effects of asymmetric experimental warming on plant phenology by testing the hypothesis that daytime warming is more effective in advancing bud break than night-time warming. Bud break was monitored daily in Picea mariana seedlings belonging to 20 provenances from Eastern Canada and subjected to daytime and night-time warming in growth chambers at temperatures varying between 8 and 16 °C. The higher advancements of bud break and shorter times required to complete the phenological phases occurred with daytime warming. Seedlings responded to night-time warming, but still with less advancement of bud break than under daytime warming. No advancement was observed when night-time warming was associated with a daytime cooling. The effect of the treatments was uniform across provenances. Our observations realized under controlled conditions allowed to experimentally demonstrate that bud break can advance under night-time warming, but to a lesser extent than under daytime warming. Prediction models using daily timescales could neglect the diverging influence of asymmetric warming and should be recalibrated for higher temporal resolutions. © 2016 John Wiley & Sons Ltd.

Comparison of occlusion break responses and vacuum rise times of phacoemulsification systems.

PubMed

Sharif-Kashani, Pooria; Fanney, Douglas; Injev, Val

2014-07-30

Occlusion break surge during phacoemulsification cataract surgery can lead to potential surgical complications. The purpose of this study was to quantify occlusion break surge and vacuum rise time of current phacoemulsification systems used in cataract surgery. Occlusion break surge at vacuum pressures between 200 and 600 mmHg was assessed with the Infiniti® Vision System, the WhiteStar Signature® Phacoemulsification System, and the Centurion® Vision System using gravity-fed fluidics. Centurion Active FluidicsTM were also tested at multiple intraoperative pressure target settings. Vacuum rise time was evaluated for Infiniti, WhiteStar Signature, Centurion, and Stellaris® Vision Enhancement systems. Rise time to vacuum limits of 400 and 600 mmHg was assessed at flow rates of 30 and 60 cc/minute. Occlusion break surge was analyzed by 2-way analysis of variance. The Centurion system exhibited substantially less occlusion break surge than the other systems tested. Surge area with Centurion Active Fluidics was similar to gravity fluidics at an equivalent bottle height. At all Centurion Active Fluidics intraoperative pressure target settings tested, surge was smaller than with Infiniti and WhiteStar Signature. Infiniti had the fastest vacuum rise time and Stellaris had the slowest. No system tested reached the 600-mmHg vacuum limit. In this laboratory study, Centurion had the least occlusion break surge and similar vacuum rise times compared with the other systems tested. Reducing occlusion break surge may increase safety of phacoemulsification cataract surgery.

Comparison of occlusion break responses and vacuum rise times of phacoemulsification systems

PubMed Central

2014-01-01

Background Occlusion break surge during phacoemulsification cataract surgery can lead to potential surgical complications. The purpose of this study was to quantify occlusion break surge and vacuum rise time of current phacoemulsification systems used in cataract surgery. Methods Occlusion break surge at vacuum pressures between 200 and 600 mmHg was assessed with the Infiniti® Vision System, the WhiteStar Signature® Phacoemulsification System, and the Centurion® Vision System using gravity-fed fluidics. Centurion Active FluidicsTM were also tested at multiple intraoperative pressure target settings. Vacuum rise time was evaluated for Infiniti, WhiteStar Signature, Centurion, and Stellaris® Vision Enhancement systems. Rise time to vacuum limits of 400 and 600 mmHg was assessed at flow rates of 30 and 60 cc/minute. Occlusion break surge was analyzed by 2-way analysis of variance. Results The Centurion system exhibited substantially less occlusion break surge than the other systems tested. Surge area with Centurion Active Fluidics was similar to gravity fluidics at an equivalent bottle height. At all Centurion Active Fluidics intraoperative pressure target settings tested, surge was smaller than with Infiniti and WhiteStar Signature. Infiniti had the fastest vacuum rise time and Stellaris had the slowest. No system tested reached the 600-mmHg vacuum limit. Conclusions In this laboratory study, Centurion had the least occlusion break surge and similar vacuum rise times compared with the other systems tested. Reducing occlusion break surge may increase safety of phacoemulsification cataract surgery. PMID:25074069

On the dispersionless Kadomtsev-Petviashvili equation with arbitrary nonlinearity and dimensionality: exact solutions, longtime asymptotics of the Cauchy problem, wave breaking and shocks

NASA Astrophysics Data System (ADS)

Santucci, F.; Santini, P. M.

2016-10-01

We study the generalization of the dispersionless Kadomtsev-Petviashvili (dKP) equation in n+1 dimensions and with nonlinearity of degree m+1, a model equation describing the propagation of weakly nonlinear, quasi one-dimensional waves in the absence of dispersion and dissipation, and arising in several physical contexts, like acoustics, plasma physics, hydrodynamics and nonlinear optics. In 2 + 1 dimensions and with quadratic nonlinearity, this equation is integrable through a novel inverse scattering transform, and it has been recently shown to be a prototype model equation in the description of the two-dimensional wave breaking of localized initial data. In higher dimensions and with higher nonlinearity, the generalized dKP equations are not integrable, but their invariance under motions on the paraboloid allows one to construct in this paper a family of exact solutions describing waves constant on their paraboloidal wave front and breaking simultaneously in all points of it, developing after breaking either multivaluedness or single-valued discontinuous profiles (shocks). Then such exact solutions are used to build the longtime behavior of the solutions of the Cauchy problem, for small and localized initial data, showing that wave breaking of small initial data takes place in the longtime regime if and only if m(n-1)≤slant 2. Lastly, the analytic aspects of such wave breaking are investigated in detail in terms of the small initial data, in both cases in which the solution becomes multivalued after breaking or it develops a shock. These results, contained in the 2012 master’s thesis of one of the authors (FS) [1], generalize those obtained in [2] for the dKP equation in n+1 dimensions with quadratic nonlinearity, and are obtained following the same strategy.

Fine-scale analysis of an assassin bug's behaviour: predatory strategies to bypass the sensory systems of prey

PubMed Central

2016-01-01

Some predators sidestep environments that render them conspicuous to the sensory systems of prey. However, these challenging environments are unavoidable for certain predators. Stenolemus giraffa is an assassin bug that feeds on web-building spiders; the web is the environment in which this predator finds its prey, but it also forms part of its preys' sophisticated sensory apparatus, blurring the distinction between environment and sensory systems. Stenolemus giraffa needs to break threads in the web that obstruct its path to the spiders, and such vibrations can alert the spiders. Using laser vibrometry, this study demonstrates how S. giraffa avoids alerting the spiders during its approach. When breaking threads, S. giraffa attenuates the vibrations produced by holding on to the loose ends of the broken thread and causing them to sag prior to release. In addition, S. giraffa releases the loose ends of a broken thread one at a time (after several seconds or minutes) and in this way spaces out the production of vibrations in time. Furthermore, S. giraffa was found to maximally reduce the amplitude of vibrations when breaking threads that are prone to produce louder vibrations. Finally, S. giraffa preferred to break threads in the presence of wind, suggesting that this araneophagic insect exploits environmental noise that temporarily impairs the spiders' ability to detect vibrations. The predatory behaviour of S. giraffa seems to be adaptated in intricate manner for bypassing the sophisticated sensory systems of web-building spiders. These findings illustrate how the physical characteristics of the environment, along with the sensory systems of prey can shape the predatory strategies of animals. PMID:27853576

Experimental evaluation of rigor mortis IX. The influence of the breaking (mechanical solution) on the development of rigor mortis.

PubMed

Krompecher, Thomas; Gilles, André; Brandt-Casadevall, Conception; Mangin, Patrice

2008-04-07

Objective measurements were carried out to study the possible re-establishment of rigor mortis on rats after "breaking" (mechanical solution). Our experiments showed that: *Cadaveric rigidity can re-establish after breaking. *A significant rigidity can reappear if the breaking occurs before the process is complete. *Rigidity will be considerably weaker after the breaking. *The time course of the intensity does not change in comparison to the controls: --the re-establishment begins immediately after the breaking; --maximal values are reached at the same time as in the controls; --the course of the resolution is the same as in the controls.

Kondo Impurities Coupled to a Helical Luttinger Liquid: RKKY-Kondo Physics Revisited.

PubMed

Yevtushenko, Oleg M; Yudson, Vladimir I

2018-04-06

We show that the paradigmatic Ruderman-Kittel-Kasuya-Yosida (RKKY) description of two local magnetic moments coupled to propagating electrons breaks down in helical Luttinger liquids when the electron interaction is stronger than some critical value. In this novel regime, the Kondo effect overwhelms the RKKY interaction over all macroscopic interimpurity distances. This phenomenon is a direct consequence of the helicity (realized, for instance, at edges of a time-reversal invariant topological insulator) and does not take place in usual (nonhelical) Luttinger liquids.

A Physicist's view on Chopin's Études

NASA Astrophysics Data System (ADS)

Blasone, Massimo

2017-07-01

We propose the use of specific dynamical processes and more in general of ideas from Physics to model the evolution in time of musical structures. We apply this approach to two Études by F. Chopin, namely Op.10 n.3 and Op.25 n.1, proposing some original description based on concepts of symmetry breaking/restoration and quantum coherence, which could be useful for interpretation. In this analysis, we take advantage of colored musical scores, obtained by implementing Scriabin's color code for sounds to musical notation.

Breaking Lorentz reciprocity to overcome the time-bandwidth limit in physics and engineering

NASA Astrophysics Data System (ADS)

Tsakmakidis, K. L.; Shen, L.; Schulz, S. A.; Zheng, X.; Upham, J.; Deng, X.; Altug, H.; Vakakis, A. F.; Boyd, R. W.

2017-06-01

A century-old tenet in physics and engineering asserts that any type of system, having bandwidth Δω, can interact with a wave over only a constrained time period Δt inversely proportional to the bandwidth (Δt·Δω ~ 2π). This law severely limits the generic capabilities of all types of resonant and wave-guiding systems in photonics, cavity quantum electrodynamics and optomechanics, acoustics, continuum mechanics, and atomic and optical physics but is thought to be completely fundamental, arising from basic Fourier reciprocity. We propose that this “fundamental” limit can be overcome in systems where Lorentz reciprocity is broken. As a system becomes more asymmetric in its transport properties, the degree to which the limit can be surpassed becomes greater. By way of example, we theoretically demonstrate how, in an astutely designed magnetized semiconductor heterostructure, the above limit can be exceeded by orders of magnitude by using realistic material parameters. Our findings revise prevailing paradigms for linear, time-invariant resonant systems, challenging the doctrine that high-quality resonances must invariably be narrowband and providing the possibility of developing devices with unprecedentedly high time-bandwidth performance.

Biological characterization of a novel in vitro cell irradiator

PubMed Central

Fowler, Tyler L.; Fisher, Michael M.; Bailey, Alison M.; Bednarz, Bryan P.

2017-01-01

To evaluate the overall robustness of a novel cellular irradiator we performed a series of well-characterized, dose-responsive assays to assess the consequences of DNA damage. We used a previously described novel irradiation system and a traditional 137Cs source to irradiate a cell line. The generation of reactive oxygen species was assessed using chloromethyl-H2DCFDA dye, the induction of DNA DSBs was observed using the comet assay, and the initiation of DNA break repair was assessed through γH2AX image cytometry. A high correlation between physical absorbed dose and biologic dose was seen for the production of intracellular reactive oxygen species, physical DNA double strand breaks, and modulation of the cellular double stand break pathway. The results compared favorably to irradiation with a traditional 137Cs source. The rapid, straightforward tests described form a reasonable approach for biologic characterization of novel irradiators. These additional testing metrics go beyond standard physics testing such as Monte Carlo simulation and thermo-luminescent dosimeter evaluation to confirm that a novel irradiator can produce the desired dose effects in vitro. Further, assessment of these biological metrics confirms that the physical handling of the cells during the irradiation process results in biologic effects that scale appropriately with dose. PMID:29232400

Fermilab Today

Science.gov Websites

Theories 3:30 p.m. DIRECTOR'S COFFEE BREAK - 2nd Flr X-Over 4:00 p.m. Accelerator Physics and Technology ; --Siri Steiner Temporary restrictions transferring disk drives If your hard drive breaks down and you try to you. They are just following a new rule. According to a recent DOE memo, no hard disk drive or

A Pilot Study of Increasing Nonpurposeful Movement Breaks at Work as a Means of Reducing Prolonged Sitting

PubMed Central

Cooley, Dean; Pedersen, Scott

2013-01-01

There is a plethora of workplace physical activity interventions designed to increase purposeful movement, yet few are designed to alleviate prolonged occupational sitting time. A pilot study was conducted to test the feasibility of a workplace e-health intervention based on a passive approach to increase nonpurposeful movement as a means of reducing sitting time. The study was trialled in a professional workplace with forty-six participants (33 females and 13 males) for a period of twenty-six weeks. Participants in the first thirteen weeks received a passive prompt every 45 minutes on their computer screen reminding them to stand and engage in nonpurposeful activity throughout their workday. After thirteen weeks, the prompt was disabled, and participants were then free to voluntary engage the software. Results demonstrated that when employees were exposed to a passive prompt, as opposed to an active prompt, they were five times more likely to fully adhere to completing a movement break every hour of the workday. Based on this pilot study, we suggest that the notion that people are willing to participate in a coercive workplace e-health intervention is promising, and there is a need for further investigation. PMID:23690798

ψ (2 S ) versus J /ψ suppression in proton-nucleus collisions from factorization violating soft color exchanges

NASA Astrophysics Data System (ADS)

Ma, Yan-Qing; Venugopalan, Raju; Watanabe, Kazuhiro; Zhang, Hong-Fei

2018-01-01

We argue that the large suppression of the ψ (2 S ) inclusive cross section relative to the J /ψ inclusive cross section in proton-nucleus (p+A) collisions can be attributed to factorization breaking effects in the formation of quarkonium. These factorization breaking effects arise from soft color exchanges between charm-anticharm pairs undergoing hadronization and comoving partons that are long lived on time scales of quarkonium formation. We compute the short distance pair production of heavy quarks in the color glass condensate (CGC) effective field theory and employ an improved color evaporation model (ICEM) to describe their hadronization into quarkonium at large distances. The combined CGC+ICEM model provides a quantitative description of J /ψ and ψ (2 S ) data in proton-proton (p+p) collisions from both RHIC and the LHC. Factorization breaking effects in hadronization, due to additional parton comovers in the nucleus, are introduced heuristically by imposing a cutoff Λ , representing the average momentum kick from soft color exchanges, in the ICEM. Such soft exchanges have no perceptible effect on J /ψ suppression in p+A collisions. In contrast, the interplay of the physics of these soft exchanges at large distances, with the physics of semihard rescattering at short distances, causes a significant additional suppression of ψ (2 S ) yields relative to that of the J /ψ . A good fit of all RHIC and LHC J /ψ and ψ (2 S ) data, for transverse momenta P⊥≤5 GeV in p+p and p+A collisions, is obtained for Λ ˜10 MeV.

The [CII]/[NII] far-infrared line ratio at z>5: extreme conditions for “normal” galaxies

NASA Astrophysics Data System (ADS)

Pavesi, Riccardo; Riechers, Dominik; Capak, Peter L.; Carilli, Chris Luke; Sharon, Chelsea E.; Stacey, Gordon J.; Karim, Alexander; Scoville, Nicholas; Smolcic, Vernesa

2017-01-01

Thanks to the Atacama Large (sub-)Millimeter Array (ALMA), observations of atomic far-infrared fine structure lines are a very productive way of measuring physical properties of the interstellar medium (ISM) in galaxies at high redshift, because they provide an unobscured view into the physical conditions of star formation. While the bright [CII] line has become a routine probe of the dynamical properties of the gas, its intensity needs to be compared to other lines in order to establish the physical origin of the emission. [NII] selectively traces the emission coming from the ionized fraction of the [CII]-emitting gas, offering insight into the phase structure of the ISM. Here we present ALMA measurements of [NII] 205 μm fine structure line emission from a representative sample of galaxies at z=5-6 spanning two orders of magnitude in star formation rate (SFR). Our results show at least two different regimes of ionized gas properties for galaxies in the first billion years of cosmic time, separated by their L[CII]/L[NII] ratio. First, we find extremely low [NII] emission compared to [CII] from a “typical” Lyman Break Galaxy (LBG-1), likely due to low dust content and reminiscent of local dwarfs. Second, the dusty Lyman Break Galaxy HZ10 and the extreme starburst AzTEC-3 show ionized gas fractions typical of local star-forming galaxies and show hints of spatial variations in their [CII]/[NII] line ratio. These observations of far-infrared lines in “normal” galaxies at z>5 yield some of the first constraints on ISM models for young galaxies in the first billion years of cosmic time and shed light on the observed evolution of the dust and gas properties.

Impacts of active school design on school-time sedentary behavior and physical activity: A pilot natural experiment.

PubMed

Brittin, Jeri; Frerichs, Leah; Sirard, John R; Wells, Nancy M; Myers, Beth M; Garcia, Jeanette; Sorensen, Dina; Trowbridge, Matthew J; Huang, Terry

2017-01-01

Children spend a significant portion of their days in sedentary behavior (SB) and on average fail to engage in adequate physical activity (PA). The school built environment may influence SB and PA, but research is limited. This natural experiment evaluated whether an elementary school designed to promote movement impacted students' school-time SB and PA. Accelerometers measured SB and PA at pre and post time-points in an intervention group who moved to the new school (n = 21) and in a comparison group experiencing no school environmental change (n = 20). Difference-in-difference (DD) analysis examined SB and PA outcomes in these groups. Measures were also collected post-intervention from an independent, grade-matched group of students in the new school (n = 21). As expected, maturational increases in SB were observed. However, DD analysis estimated that the intervention attenuated increase in SB by 81.2 ± 11.4 minutes/day (p<0.001), controlling for time in moderate to vigorous physical activity (MVPA). The intervention was also estimated to increase daily number of breaks from SB by 23.4 ± 2.6 (p < .001) and to increase light physical activity (LPA) by 67.7 ± 10.7 minutes/day (p<0.001). However, the intervention decreased MVPA by 10.3 ± 2.3 minutes/day (p<0.001). Results of grade-matched independent samples analysis were similar, with students in the new vs. old school spending 90.5 ± 16.1 fewer minutes/day in SB, taking 21.1 ± 2.7 more breaks from SB (p<0.001), and spending 64.5 ± 14.8 more minutes in LPA (p<0.001), controlling for time in MVPA. Students in the new school spent 13.1 ± 2.7 fewer minutes in MVPA (p<0.001) than their counterparts in the old school. This pilot study found that active school design had beneficial effects on SB and LPA, but not on MVPA. Mixed results point to a need for active classroom design strategies to mitigate SB, and quick access from classrooms to areas permissive of high-intensity activities to promote MVPA. Integrating active design with programs/policies to promote PA may yield greatest impact on PA of all intensities.

Impacts of active school design on school-time sedentary behavior and physical activity: A pilot natural experiment

PubMed Central

Frerichs, Leah; Sirard, John R.; Wells, Nancy M.; Myers, Beth M.; Garcia, Jeanette; Sorensen, Dina; Trowbridge, Matthew J.; Huang, Terry

2017-01-01

Background Children spend a significant portion of their days in sedentary behavior (SB) and on average fail to engage in adequate physical activity (PA). The school built environment may influence SB and PA, but research is limited. This natural experiment evaluated whether an elementary school designed to promote movement impacted students’ school-time SB and PA. Methods Accelerometers measured SB and PA at pre and post time-points in an intervention group who moved to the new school (n = 21) and in a comparison group experiencing no school environmental change (n = 20). Difference-in-difference (DD) analysis examined SB and PA outcomes in these groups. Measures were also collected post-intervention from an independent, grade-matched group of students in the new school (n = 21). Results As expected, maturational increases in SB were observed. However, DD analysis estimated that the intervention attenuated increase in SB by 81.2 ± 11.4 minutes/day (p<0.001), controlling for time in moderate to vigorous physical activity (MVPA). The intervention was also estimated to increase daily number of breaks from SB by 23.4 ± 2.6 (p < .001) and to increase light physical activity (LPA) by 67.7 ± 10.7 minutes/day (p<0.001). However, the intervention decreased MVPA by 10.3 ± 2.3 minutes/day (p<0.001). Results of grade-matched independent samples analysis were similar, with students in the new vs. old school spending 90.5 ± 16.1 fewer minutes/day in SB, taking 21.1 ± 2.7 more breaks from SB (p<0.001), and spending 64.5 ± 14.8 more minutes in LPA (p<0.001), controlling for time in MVPA. Students in the new school spent 13.1 ± 2.7 fewer minutes in MVPA (p<0.001) than their counterparts in the old school. Conclusions This pilot study found that active school design had beneficial effects on SB and LPA, but not on MVPA. Mixed results point to a need for active classroom design strategies to mitigate SB, and quick access from classrooms to areas permissive of high-intensity activities to promote MVPA. Integrating active design with programs/policies to promote PA may yield greatest impact on PA of all intensities. PMID:29216300

On the Nature of the Variability Power Decay towards Soft Spectral States in X-Ray Binaries. Case Study in Cyg X-1

NASA Technical Reports Server (NTRS)

Titarchuk, Lev; Shaposhinikov, Nikolai

2007-01-01

A characteristic feature of the Fourier Power Density Spectrum (PDS) observed from black hole X-ray binaries in low/hard and intermediate spectral states is a broad band-limited noise, characterized by a constant below some frequency (a "break" frequency) and a power law above this frequency. It has been shown that the variability of this type can be produced by the inward diffusion of the local driving perturbations in a bounded configuration (accretion disk or corona). In the framework of this model, the perturbation diffusion time to is related to the phenomenological break frequency, while the PDS power-law slope above the "break" is determined by the viscosity distribution over the configuration. The perturbation diffusion scenario explains the decay of the power of X-ray variability observed in a number of compact sources (containing black hole and neutron star) during an evolution of theses sources from low/hard to high/soft states. We compare the model predictions with the subset of data from Cyg X-1 collected by the Rossi X-ray Time Explorer (RXTE). Our extensive analysis of the Cyg X-1 PDSs demonstrates that the observed integrated power P(sub x), decreases approximately as a square root of the characteristic frequency of the driving oscillations v(sub dr). The RXTE observations of Cyg X-1 allow us to infer P(sub dr), and t(sub o) as a function of v(sub dr). We also apply the basic parameters of observed PDSs, power-law index and low frequency quasiperiodic oscillations. to infer Reynolds (Re) number from the observations using the method developed in our previous paper. Our analysis shows that Re-number increases from values about 10 in low/hard state to that about 70 during the high/soft state. Subject headings: accretion, accretion disks-black hole physics-stars:individual (Cyg X-1) :radiation mechanisms: nonthermal-physical data and processes

Cosmological texture is incompatible with Planck-scale physics

NASA Technical Reports Server (NTRS)

Holman, Richard; Hsu, Stephen D. H.; Kolb, Edward W.; Watkins, Richard; Widrow, Lawrence M.

1992-01-01

Nambu-Goldstone modes are sensitive to the effects of physics at energies comparable to the scale of spontaneous symmetry breaking. We show that as a consequence of this the global texture proposal for structure formation requires rather severe assumptions about the nature of physics at the Planck scale.

Student Motivation in Physical Education: Breaking down Barriers

ERIC Educational Resources Information Center

Mowling, Claire M.; Brock, Sheri J.; Eiler, Kim K.; Rudisill, Mary E.

2004-01-01

A fundamental characteristic of a successful physical education program is that the students are interested and motivated to learn the intended objectives. Unfortunately, in many cases, students begin losing interest in physical education as they progress through school. In order to better understand this phenomenon, the authors explored the…

Nonergodic property of the space-time coupled CTRW: Dependence on the long-tailed property and correlation

NASA Astrophysics Data System (ADS)

Liu, Jian; Li, Baohe; Chen, Xiaosong

2018-02-01

The space-time coupled continuous time random walk model is a stochastic framework of anomalous diffusion with many applications in physics, geology and biology. In this manuscript the time averaged mean squared displacement and nonergodic property of a space-time coupled continuous time random walk model is studied, which is a prototype of the coupled continuous time random walk presented and researched intensively with various methods. The results in the present manuscript show that the time averaged mean squared displacements increase linearly with lag time which means ergodicity breaking occurs, besides, we find that the diffusion coefficient is intrinsically random which shows both aging and enhancement, the analysis indicates that the either aging or enhancement phenomena are determined by the competition between the correlation exponent γ and the waiting time's long-tailed index α.

Climate and floods still govern California levee breaks

USGS Publications Warehouse

Florsheim, J.L.; Dettinger, M.D.

2007-01-01

Even in heavily engineered river systems, climate still governs flood variability and thus still drives many levee breaks and geomorphic changes. We assemble a 155-year record of levee breaks for a major California river system to find that breaks occurred in 25% of years during the 20th Century. A relation between levee breaks and river discharge is present that sets a discharge threshold above which most levee breaks occurred. That threshold corresponds to small floods with recurrence intervals of ???2-3 years. Statistical analysis illustrates that levee breaks and peak discharges cycle (broadly) on a 12-15 year time scale, in time with warm-wet storm patterns in California, but more slowly or more quickly than ENSO and PDO climate phenomena, respectively. Notably, these variations and thresholds persist through the 20th Century, suggesting that historical flood-control effects have not reduced the occurrence or frequency of levee breaks. Copyright 2007 by the American Geophysical Union.

Planck 2010

ScienceCinema

None

2017-12-09

Planck 2010 From the Planck Scale to the ElectroWeak Scale The conference will be the twelfth one in a series of meetings on physics beyond the Standard Model, organized jointly by several European groups: Bonn, CERN, Ecole Polytechnique, ICTP, Madrid, Oxford, Padua, Pisa, SISSA and Warsaw as part of activities in the framework of the European network UNILHC.Topics to be discussed: Supersymmetry Supergravity & string phenomenology Extra dimensions Electroweak symmetry breaking LHC and Tevatron Physics Collider physics Flavor & neutrinos physics Astroparticle & cosmology Gravity & holography Strongly coupled physics & CFT Registration: registration will be open until May 1st. Registration fees amount to 150 CHF and cover the cost of the coffee breaks and the social dinner. Payment has to be made online. The deadline for registration has been postponed to May 7th. However, after May 3th, we shall not accept any talk request any more. The meeting will be partly supported by ° the Marie Curie Initial Training Network "UNILHC" PITN-GA-2009-23792, ° the ERC Advanced Grant "MassTeV" 226371, ° and the CERN-TH unit.

Can a Double Component Outflow Explain the X-Ray and Optical Lightcurves of Swift Gamma-Ray Bursts?

NASA Technical Reports Server (NTRS)

De Pasquale, Massimiliano; Evans, P.; Oates, S.; Page, M.; Zane, S.; Schady, P.; Breeveld, A.; Holland, S.; Still, M.

2011-01-01

An increasing sample of Gamma-Ray Bursts (GRBs) observed by Swift show evidence of 'chromatic breaks', i.e. breaks that are present in the X-ray but not in the optical. We find that in a significant fraction of these GRB afterglows the X-ray and the optical emission cannot be produced by the same component. We propose that these afterglow lightcurves are the result of a two-component jet, in which both components undergo energy injection for the whole observation and the X-ray break is due to a jet break in the narrow outflow. Bursts with chromatic breaks also explain another surprising finding, the paucity of late achromatic breaks. We propose a model that may explain the behaviour of GRB emission in both X-ray and optical bands. This model can be a radical and noteworthy alternative to the current interpretation for the 'canonical' XRT and UVOT lightcurves, and it bears fundamental implications for GRB physics.

The UP4FUN Intervention Effect on Breaking Up Sedentary Time in 10- to 12-Year-Old Belgian Children: The ENERGY-Project.

PubMed

Verloigne, Maïté; Berntsen, Sveinung; Ridgers, Nicola D; Cardon, Greet; Chinapaw, Mai; Altenburg, Teatske; Brug, Johannes; Bere, Elling; De Bourdeaudhuij, Ilse; Van Lippevelde, Wendy; Maes, Lea

2015-05-01

There are currently no studies available reporting intervention effects on breaking up children's sedentary time. This study examined the UP4FUN intervention effect on objectively measured number of breaks in sedentary time, number of sedentary bouts (≥ 10 mins) and total and average amount of time spent in those sedentary bouts among 10- to 12-year-old Belgian children. The total sample included 354 children (mean age: 10.9 ± 0.7 years; 59% girls) with valid ActiGraph accelerometer data at pre- and posttest. Only few and small intervention effects were found, namely on total time spent in sedentary bouts immediately after school hours (4-6PM; β = -3.51mins) and on average time spent in sedentary bouts before school hours (6-8.30AM; β = -4.83mins) and immediately after school hours in favor of children from intervention schools (β = -2.71mins). Unexpectedly, girls from intervention schools decreased the number of breaks during school hours (8.30AM-4PM; β = -23.45breaks) and increased the number of sedentary bouts on a weekend day (β = +0.90bouts), whereas girls in control schools showed an increase in number of breaks and a decrease in number of bouts. In conclusion, UP4FUN did not have a consistent or substantial effect on breaking up children's sedentary time and these data suggest that more intensive and longer lasting interventions are needed.

A Model for Reform. Two-Year Colleges in the Twenty-First Century: Breaking Down Barriers (TYC21).

ERIC Educational Resources Information Center

Palmer, James C., Ed.

This book describes the TYC21 project (Two-Year Colleges in the Twenty-First Century: Breaking Down Barriers), which provided a framework to implement reform in science, engineering, and physics education at two-year colleges via the cooperative efforts of faculty in cross-educational activities. The project sought to increase the quality of…

Critical wind speed at which trees break

NASA Astrophysics Data System (ADS)

Virot, E.; Ponomarenko, A.; Dehandschoewercker, É.; Quéré, D.; Clanet, C.

2016-02-01

Data from storms suggest that the critical wind speed at which trees break is constant (≃42 m /s ), regardless of tree characteristics. We question the physical origin of this observation both experimentally and theoretically. By combining Hooke's law, Griffith's criterion, and tree allometry, we show that the critical wind speed indeed hardly depends on the height, diameter, and elastic properties of trees.

Critical wind speed at which trees break.

PubMed

Virot, E; Ponomarenko, A; Dehandschoewercker, É; Quéré, D; Clanet, C

2016-02-01

Data from storms suggest that the critical wind speed at which trees break is constant (≃42m/s), regardless of tree characteristics. We question the physical origin of this observation both experimentally and theoretically. By combining Hooke's law, Griffith's criterion, and tree allometry, we show that the critical wind speed indeed hardly depends on the height, diameter, and elastic properties of trees.

Developing Model-Making and Model-Breaking Skills Using Direct Measurement Video-Based Activities

ERIC Educational Resources Information Center

Vonk, Matthew; Bohacek, Peter; Militello, Cheryl; Iverson, Ellen

2017-01-01

This study focuses on student development of two important laboratory skills in the context of introductory college-level physics. The first skill, which we call model making, is the ability to analyze a phenomenon in a way that produces a quantitative multimodal model. The second skill, which we call model breaking, is the ability to critically…

Combined effect of pH and heating conditions on the physical properties of Alaska pollock surimi gels.

PubMed

Lee, Myeong Gi; Yoon, Won Byong; Park, Jae W

2017-06-01

Physical properties of Alaska pollock surimi paste were investigated as affected by pH (4.0 and 6.0-10.0) and heating conditions (slow and fast). The highest values of gel strength and deformability, as shown by breaking force and penetration distance, were obtained at pH 7.5-8.0, while the lowest values were at pH 10.0 followed by pH 6.0 and pH 6.5, respectively. Two-step slow heating process increased the breaking strength value nearly two times higher than one-step fast heating. The effect of pH was strikingly high at pH 7.5 when gels were prepared using 2-step heating, indicating the pH dependence of endogenous transglutaminase. However, the highest gel strength was obtained at pH 8.0 when gels were prepared in fast heating. Whiteness value (L - 3b*) increased significantly (p < .05) as pH increased from 6.0 to 6.5, but thereafter decreased significantly (p < .05) as pH increased. L* value (lightness) and b* value (yellowness) continuously decreased as the pH is shifted from 6.0 to 10. Fast heated gels showed the lowest yellowness, resulting in whiter appearance, probably due to the effect of reduced browning reaction. The uniqueness of this study was to measure the combined effect of pH and heating conditions on the gel texture and color. There were various studies dealing with pH or heating conditions independently. As the primary character for surimi seafood is gel texture and color. The highest values of gel strength and deformability, as shown by breaking force and penetration distance, were obtained at pH 7.5-8.0, while the lowest values were at pH 10.0 followed by pH 6.0 and pH 6.5, respectively. Two-step slow heating process increased the breaking strength value nearly two times higher than one-step fast heating. Whiteness value (L - 3b*) increased significantly as pH increased from 6.0 to 6.5, but thereafter decreased significantly as pH increased. L* value (lightness) and b* value (yellowness) continuously decreased as the pH is shifted from 6.0 to 10. Fast heated gels showed the lowest yellowness, resulting in whiter appearance. © 2016 Wiley Periodicals, Inc.

Physics at high energy photon photon colliders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chanowitz, M.S.

I review the physic prospects for high energy photon photon colliders, emphasizing results presented at the LBL Gamma Gamma Collider Workshop. Advantages and difficulties are reported for studies of QCD, the electroweak gauge sector, supersymmetry, and electroweak symmetry breaking.

Child personality facets and overreactive parenting as predictors of aggression and rule-breaking trajectories from childhood to adolescence.

PubMed

Becht, Andrik I; Prinzie, Peter; Deković, Maja; van den Akker, Alithe L; Shiner, Rebecca L

2016-05-01

This study examined trajectories of aggression and rule breaking during the transition from childhood to adolescence (ages 9-15), and determined whether these trajectories were predicted by lower order personality facets, overreactive parenting, and their interaction. At three time points separated by 2-year intervals, mothers and fathers reported on their children's aggression and rule breaking (N = 290, M age = 8.8 years at Time 1). At Time 1, parents reported on their children's personality traits and their own overreactivity. Growth mixture modeling identified three aggression trajectories (low decreasing, high decreasing, and high increasing) and two rule-breaking trajectories (low and high). Lower optimism and compliance and higher energy predicted trajectories for both aggression and rule breaking, whereas higher expressiveness and irritability and lower orderliness and perseverance were unique risk factors for increasing aggression into adolescence. Lower concentration was a unique risk factor for increasing rule breaking. Parental overreactivity predicted higher trajectories of aggression but not rule breaking. Only two Trait × Overreactivity interactions were found. Our results indicate that personality facets could differentiate children at risk for different developmental trajectories of aggression and rule breaking.

The effect of physical activity on sleep quality, well-being, and affect in academic stress periods.

PubMed

Wunsch, Kathrin; Kasten, Nadine; Fuchs, Reinhard

2017-01-01

The stress-buffering hypothesis postulates that physical activity and exercise can buffer the negative effects of (academic) stress on health. It still remains an open question whether students, who regularly engage in physical activity and exercise within their academic examination period, can successfully diminish these negative effects. Sixty-four subjects participated in this study and completed a total of five surveys, with T1 at the end of the semester break (baseline) and T2-T5 being presented every Friday in the last 4 weeks of the semester (examination period). They were asked to answer questions about their activity level, sleep quality, well-being and affect. Hierarchical linear models showed significant dependencies on time for all dependent measures. The expansion of the model for exercise also showed significant main effects of this predictor on well-being and positive affect (PA) and negative affect. Moreover, significant interactions with time for sleep quality and PA were found. Results suggest that physical activity and exercise in the academic examination period may be able to buffer the negative effects of stress on health-related outcomes. Therefore, activity levels should be maintained in times of high stress to prevent negative effects on sleep, well-being and affect in students.

Symmetry breaking and the geometry of reduced density matrices

NASA Astrophysics Data System (ADS)

Zauner, V.; Draxler, D.; Vanderstraeten, L.; Haegeman, J.; Verstraete, F.

2016-11-01

The concept of symmetry breaking and the emergence of corresponding local order parameters constitute the pillars of modern day many body physics. We demonstrate that the existence of symmetry breaking is a consequence of the geometric structure of the convex set of reduced density matrices of all possible many body wavefunctions. The surfaces of these convex bodies exhibit non-analyticities, which signal the emergence of symmetry breaking and of an associated order parameter and also show different characteristics for different types of phase transitions. We illustrate this with three paradigmatic examples of many body systems exhibiting symmetry breaking: the quantum Ising model, the classical q-state Potts model in two-dimensions at finite temperature and the ideal Bose gas in three-dimensions at finite temperature. This state based viewpoint on phase transitions provides a unique novel tool for studying exotic many body phenomena in quantum and classical systems.

Spontaneous chiral symmetry breaking in metamaterials

NASA Astrophysics Data System (ADS)

Liu, Mingkai; Powell, David A.; Shadrivov, Ilya V.; Lapine, Mikhail; Kivshar, Yuri S.

2014-07-01

Spontaneous chiral symmetry breaking underpins a variety of areas such as subatomic physics and biochemistry, and leads to an impressive range of fundamental phenomena. Here we show that this prominent effect is now available in artificial electromagnetic systems, enabled by the advent of magnetoelastic metamaterials where a mechanical degree of freedom leads to a rich variety of strong nonlinear effects such as bistability and self-oscillations. We report spontaneous symmetry breaking in torsional chiral magnetoelastic structures where two or more meta-molecules with opposite handedness are electromagnetically coupled, modifying the system stability. Importantly, we show that chiral symmetry breaking can be found in the stationary response of the system, and the effect is successfully demonstrated in a microwave pump-probe experiment. Such symmetry breaking can lead to a giant nonlinear polarization change, energy localization and mode splitting, which provides a new possibility for creating an artificial phase transition in metamaterials, analogous to that in ferrimagnetic domains.

Spontaneous chiral symmetry breaking in metamaterials.

PubMed

Liu, Mingkai; Powell, David A; Shadrivov, Ilya V; Lapine, Mikhail; Kivshar, Yuri S

2014-07-18

Spontaneous chiral symmetry breaking underpins a variety of areas such as subatomic physics and biochemistry, and leads to an impressive range of fundamental phenomena. Here we show that this prominent effect is now available in artificial electromagnetic systems, enabled by the advent of magnetoelastic metamaterials where a mechanical degree of freedom leads to a rich variety of strong nonlinear effects such as bistability and self-oscillations. We report spontaneous symmetry breaking in torsional chiral magnetoelastic structures where two or more meta-molecules with opposite handedness are electromagnetically coupled, modifying the system stability. Importantly, we show that chiral symmetry breaking can be found in the stationary response of the system, and the effect is successfully demonstrated in a microwave pump-probe experiment. Such symmetry breaking can lead to a giant nonlinear polarization change, energy localization and mode splitting, which provides a new possibility for creating an artificial phase transition in metamaterials, analogous to that in ferrimagnetic domains.

Symmetry Breaking of Counter-Propagating Light in a Nonlinear Resonator.

PubMed

Del Bino, Leonardo; Silver, Jonathan M; Stebbings, Sarah L; Del'Haye, Pascal

2017-02-21

Spontaneous symmetry breaking is a concept of fundamental importance in many areas of physics, underpinning such diverse phenomena as ferromagnetism, superconductivity, superfluidity and the Higgs mechanism. Here we demonstrate nonreciprocity and spontaneous symmetry breaking between counter-propagating light in dielectric microresonators. The symmetry breaking corresponds to a resonance frequency splitting that allows only one of two counter-propagating (but otherwise identical) states of light to circulate in the resonator. Equivalently, this effect can be seen as the collapse of standing waves and transition to travelling waves within the resonator. We present theoretical calculations to show that the symmetry breaking is induced by Kerr-nonlinearity-mediated interaction between the counter-propagating light. Our findings pave the way for a variety of applications including optically controllable circulators and isolators, all-optical switching, nonlinear-enhanced rotation sensing, optical flip-flops for photonic memories as well as exceptionally sensitive power and refractive index sensors.

Symmetry Breaking of Counter-Propagating Light in a Nonlinear Resonator

PubMed Central

Del Bino, Leonardo; Silver, Jonathan M.; Stebbings, Sarah L.; Del'Haye, Pascal

2017-01-01

Spontaneous symmetry breaking is a concept of fundamental importance in many areas of physics, underpinning such diverse phenomena as ferromagnetism, superconductivity, superfluidity and the Higgs mechanism. Here we demonstrate nonreciprocity and spontaneous symmetry breaking between counter-propagating light in dielectric microresonators. The symmetry breaking corresponds to a resonance frequency splitting that allows only one of two counter-propagating (but otherwise identical) states of light to circulate in the resonator. Equivalently, this effect can be seen as the collapse of standing waves and transition to travelling waves within the resonator. We present theoretical calculations to show that the symmetry breaking is induced by Kerr-nonlinearity-mediated interaction between the counter-propagating light. Our findings pave the way for a variety of applications including optically controllable circulators and isolators, all-optical switching, nonlinear-enhanced rotation sensing, optical flip-flops for photonic memories as well as exceptionally sensitive power and refractive index sensors. PMID:28220865

Breaking Barriers: Women-Centered Physical Education Programming in Higher Education

ERIC Educational Resources Information Center

Foster, Elaine; Appleby, Karen M.

2015-01-01

In general, physical activity subsides for females after high school. Researchers have found that women experience unique barriers to remaining physically active during their college years. Obstacles such as social anxiety, lack of social support, and life balance have been cited as challenges for women in relation to maintaining consistent…

Effectiveness of a Worksite Social & Physical Environment Intervention on Need for Recovery, Physical Activity and Relaxation; Results of a Randomized Controlled Trial

PubMed Central

Coffeng, Jennifer K.; Boot, Cécile R. L.; Duijts, Saskia F. A.; Twisk, Jos W. R.; van Mechelen, Willem; Hendriksen, Ingrid J. M.

2014-01-01

Objective To investigate the effectiveness of a worksite social and physical environment intervention on need for recovery (i.e., early symptoms of work-related mental and physical fatigue), physical activity and relaxation. Also, the effectiveness of the separate interventions was investigated. Methods In this 2×2 factorial design study, 412 office employees from a financial service provider participated. Participants were allocated to the combined social and physical intervention, to the social intervention only, to the physical intervention only or to the control group. The primary outcome measure was need for recovery. Secondary outcomes were work-related stress (i.e., exhaustion, detachment and relaxation), small breaks, physical activity (i.e., stair climbing, active commuting, sport activities, light/moderate/vigorous physical activity) and sedentary behavior. Outcomes were measured by questionnaires at baseline, 6 and 12 months follow-up. Multilevel analyses were performed to investigate the effects of the three interventions. Results In all intervention groups, a non-significant reduction was found in need for recovery. In the combined intervention (n = 92), exhaustion and vigorous physical activities decreased significantly, and small breaks at work and active commuting increased significantly compared to the control group. The social intervention (n = 118) showed a significant reduction in exhaustion, sedentary behavior at work and a significant increase in small breaks at work and leisure activities. In the physical intervention (n = 96), stair climbing at work and active commuting significantly increased, and sedentary behavior at work decreased significantly compared to the control group. Conclusion None of the interventions was effective in improving the need for recovery. It is recommended to implement the social and physical intervention among a population with higher baseline values of need for recovery. Furthermore, the intervention itself could be improved by increasing the intensity of the intervention (for example weekly GMI-sessions), providing physical activity opportunities and exercise schemes, and by more drastic environment interventions (restructuring entire department floor). Trial Registration Nederlands Trial Register NTR2553 PMID:25542039

Superconducting properties of lithographic lead break junctions

NASA Astrophysics Data System (ADS)

Weber, David; Scheer, Elke

2018-01-01

We have fabricated mechanically controlled break junction samples made of lead (Pb) by means of state-of-the-art nanofabrication methods: electron beam lithography and physical vapour deposition. The electrical and magnetic properties were characterized in a {}3{He} cryostat and showed a hard superconducting gap. Temperature and magnetic field dependence of tunnel contacts were compared and quantitatively described by including either thermal broadening of the density of states or pair breaking in the framework of a Skalski model, respectively. We show point contact spectra of few-atom contacts and present tunneling spectra exhibiting a superconducting double-gap structure.

Regular activity breaks combined with physical activity improve postprandial plasma triglyceride, nonesterified fatty acid, and insulin responses in healthy, normal weight adults: A randomized crossover trial.

PubMed

Homer, Ashleigh R; Fenemor, Stephen P; Perry, Tracy L; Rehrer, Nancy J; Cameron, Claire M; Skeaff, C Murray; Peddie, Meredith C

Compared with prolonged sitting, regular activity breaks immediately lower postprandial glucose and insulin, but not triglyceride responses. Postprandial triglycerides can be lowered by physical activity but the effect is often delayed by ∼12 to 24 hours. The objective of the study was to determine whether regular activity breaks affect postprandial triglyceride response in a delayed manner similar to physical activity. In a randomized crossover trial, 36 adults (body mass index 23.9 kg/m 2 [standard deviation 3.9]) completed four 2-day interventions: (1) prolonged sitting (SIT); (2) prolonged sitting with 30 minutes of continuous walking (60% VO 2max ), at the end of Day 1 (SIT + PA D1 ); (3) Sitting with 2 minutes of walking (60% VO 2max ) every 30 minutes (RAB); (4) A combination of the continuous walking and regular activity breaks in 2 and 3 above (RAB + PA D1 ). Postprandial plasma triglyceride, nonesterified fatty acids, glucose, and insulin responses were measured in venous blood over 5 hours on Day 2. Compared with SIT, both RAB (difference: -43.61 mg/dL·5 hours; 95% confidence interval [CI] -83.66 to -2.67; P = .035) and RAB + PA D1 (-65.86 mg/dL·5 hours; 95% CI -112.14 to -19.58; P = .005) attenuated triglyceride total area under the curve (tAUC). RAB + PA D1 produced the greatest reductions in insulin tAUC (-23%; 95% CI -12% to -31%; P < .001), whereas RAB resulted in the largest increase in nonesterified fatty acids (tAUC, 10.08 mg/dL·5 hours; 95% CI 5.60-14.84; P < .001). There was no effect on glucose tAUC (P = .290). Postprandial triglyceride response is attenuated by regular activity breaks, when measured ∼24 hours after breaks begin. Combining regular activity breaks with 30 minutes of continuous walking further improves insulinemic and lipidemic responses. Copyright © 2017 National Lipid Association. Published by Elsevier Inc. All rights reserved.

The Decompression Sickness and Venous Gas Emboli Consequences of Air Breaks During 100% Oxygen Prebreathe

NASA Technical Reports Server (NTRS)

Conkin, J.; Gernhardt, M. L.; Powell, M. R.

2004-01-01

Not enough is known about the increased risk of hypobaric decompression sickness (DCS) and production of venous (VGE) and arterial (AGE) gas emboli following an air break in an otherwise normal 100% resting oxygen (O2) prebreathe (PB), and certainly a break in PB when exercise is used to accelerate nitrogen (N2) elimination from the tissues. Current Aeromedical Flight Rules at the Johnson Space Center about additional PB payback times are untested, possibly too conservative, and therefore not optimized for operational use. A 10 min air break at 90 min into a 120 min PB that includes initial dual-cycle ergometry for 10 min will show a measurable increase in the risk of DCS and VGE after ascent to 4.3 psia compared to a 10 min break at 15 min into the PB, or when there is no break in PB. Data collection with humans begins in 2005, but here we first evaluate the hypothesis using three models of tissue N2 kinetics: Model I is a simple single half-time compartment exponential model, Model II is a three compartment half-time exponential model, and Model III is a variable half-time compartment model where the percentage of maximum O2 consumption for the subject during dual-cycle ergometry exercise defines the half-time compartment. Model I with large rate constants to simulate an exercise effect always showed a late break in PB had the greatest consequence. Model II showed an early break had the greatest consequence. Model III showed there was no difference between early or late break in exercise PB. Only one of these outcomes will be observed when humans are tested. Our results will favor one of these models, and so advance our understanding of tissue N2 kinetics, and of altitude DCS after an air break in PB.

Coupled calculation of the radiological release and the thermal-hydraulic behavior of a 3-loop PWR after a SGTR by means of the code RELAP5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Hove, W.; Van Laeken, K.; Bartsoen, L.

1995-09-01

To enable a more realistic and accurate calculation of the radiological consequences of a SGTR, a fission product transport model was developed. As the radiological releases strongly depend on the thermal-hydraulic transient, the model was included in the RELAP5 input decks of the Belgian NPPs. This enables the coupled calculation of the thermal-hydraulic transient and the radiological release. The fission product transport model tracks the concentration of the fission products in the primary circuit, in each of the SGs as well as in the condenser. This leads to a system of 6 coupled, first order ordinary differential equations with timemore » dependent coefficients. Flashing, scrubbing, atomisation and dry out of the break flow are accounted for. Coupling with the thermal-hydraulic calculation and correct modelling of the break position enables an accurate calculation of the mixture level above the break. Pre- and post-accident spiking in the primary circuit are introduced. The transport times in the FW-system and the SG blowdown system are also taken into account, as is the decontaminating effect of the primary make-up system and of the SG blowdown system. Physical input parameters such as the partition coefficients, half life times and spiking coefficients are explicitly introduced so that the same model can be used for iodine, caesium and noble gases.« less

Temporal profile of prolonged, night-time driving performance: breaks from driving temporarily reduce time-on-task fatigue but not sleepiness.

PubMed

Phipps-Nelson, Jo; Redman, Jennifer R; Rajaratnam, Shantha M W

2011-09-01

Breaks are often used by drivers to counteract sleepiness and time-on-task fatigue during prolonged driving. We examined the temporal profile of changes in driving performance, electroencephalogram (EEG) activity and subjective measures of sleepiness and fatigue during prolonged nocturnal driving in a car simulator. In addition, the study examined the impact of regular breaks from driving on performance, sleepiness and fatigue. Healthy volunteers (n=12, 23-45 years) maintained a regular sleep-wake pattern for 14 days and were then in a laboratory from 21:00 to 08:30 hours. The driving simulator scene was designed to simulate monotonous night-time rural driving. Participants drove 4 × 2-h test sessions, with a break from driving of 1 h between each session. During the break participants performed tests assessing sleepiness and fatigue, and psychomotor performance (~30 mins), and then were permitted to sit quietly. They were monitored for wakefulness, and not permitted to nap or ingest caffeine. EEG was recorded during the driving task, and subjective assessments of sleepiness and fatigue were obtained at the start and completion of each session. We found that driving performance deteriorated (2.5-fold), EEG delta, theta and alpha activity increased, and subjective sleepiness and fatigue ratings increased across the testing period. Driving performance and fatigue ratings improved following the scheduled breaks from driving, while the breaks did not affect EEG activity and subjective sleepiness. Time-on-task effects increased through the testing period, indicating that these effects are exacerbated by increasing sleepiness. Breaks from driving without sleep temporarily ameliorate time-on-task fatigue, but provide little benefit to the sleepy driver. © 2010 European Sleep Research Society.

Rejoining of isochromatid breaks induced by heavy ions in G2-phase normal human fibroblasts

NASA Technical Reports Server (NTRS)

Kawata, T.; Durante, M.; Furusawa, Y.; George, K.; Ito, H.; Wu, H.; Cucinotta, F. A.

2001-01-01

We reported previously that exposure of normal human fibroblasts in G2 phase of the cell cycle to high-LET radiation produces a much higher frequency of isochromatid breaks than exposure to gamma rays. We concluded that an increase in the production of isochromatid breaks is a signature of initial high-LET radiation-induced G2-phase damage. In this paper, we report the repair kinetics of isochromatid breaks induced by high-LET radiation in normal G2-phase human fibroblasts. Exponentially growing human fibroblasts (AG1522) were irradiated with gamma rays or energetic carbon (290 MeV/nucleon), silicon (490 MeV/nucleon), or iron (200 MeV/nucleon) ions. Prematurely condensed chromosomes were induced by calyculin A after different postirradiation incubation times ranging from 0 to 600 min. Chromosomes were stained with Giemsa, and aberrations were scored in cells at G2 phase. G2-phase fragments, the result of the induction of isochromatid breaks, decreased quickly with incubation time. The curve for the kinetics of the rejoining of chromatid-type breaks showed a slight upward curvature with time after exposure to 440 keV/microm iron particles, probably due to isochromatid-isochromatid break rejoining. The formation of chromatid exchanges after exposure to high-LET radiation therefore appears to be underestimated, because isochromatid-isochromatid exchanges cannot be detected. Increased induction of isochromatid breaks and rejoining of isochromatid breaks affect the overall kinetics of chromatid-type break rejoining after exposure to high-LET radiation.

Contextual factors related to implementation of classroom physical activity breaks.

PubMed

Carlson, Jordan A; Engelberg, Jessa K; Cain, Kelli L; Conway, Terry L; Geremia, Carrie; Bonilla, Edith; Kerner, Jon; Sallis, James F

2017-09-01

Brief structured physical activity in the classroom is effective for increasing student physical activity. The present study investigated the association between implementation-related contextual factors and intervention implementation after adoption of a structured classroom physical activity intervention. Six elementary-school districts adopted structured classroom physical activity programs in 2013-2014. Implementation contextual factors and intervention implementation (structured physical activity provided in past week or month, yes/no) were assessed using surveys of 337 classroom teachers from 24 schools. Mixed-effects models accounted for the nested design. Availability of resources (yes/no, ORs = 1.91-2.93) and implementation climate z-scores (ORs = 1.36-1.47) were consistently associated with implementation. Teacher-perceived classroom behavior benefits (OR = 1.29) but not student enjoyment or health benefits, and time (OR = 2.32) and academic (OR = 1.63) barriers but not student cooperation barriers were associated with implementation (all z-scores). Four implementation contextual factor composites had an additive association with implementation (OR = 1.64 for each additional favorable composite). Training and technical assistance alone may not support a large proportion of teachers to implement structured classroom physical activity. In addition to lack of time and interference with academic lessons, school climate related to whether administrators and other teachers were supportive of the intervention were key factors explaining whether teachers implemented the intervention. Evidence-based implementation strategies are needed for effectively communicating the benefits of classroom physical activity on student behavior and improving teacher and administrator climate/attitudes around classroom physical activity.

Estimating the cost of production stoppage

NASA Technical Reports Server (NTRS)

Delionback, L. M.

1979-01-01

Estimation model considers learning curve quantities, and time of break to forecast losses due to break in production schedule. Major parameters capable of predicting costs are number of units made prior to production sequence, length of production break, and slope of learning curve produced prior to break.

Assessing Alternative Breaks: Moving beyond Sleeping on Floors and Pass-the-Candle Reflection

ERIC Educational Resources Information Center

Porter, Melody C.

2011-01-01

Alternative breaks (ABs) often bring a smattering of images to mind: college students in matching T-shirts, cramped vans, well-used work gloves, physical labor, and, perhaps, way too much peanut butter. All of these images are at least in part accurate for the AB program at the College of William and Mary. Add to them a strong sense that sending…

Moving Physical Activity beyond the School Classroom: A Social-Ecological Insight for Teachers of the Facilitators and Barriers to Students' Non-Curricular Physical Activity

ERIC Educational Resources Information Center

Hyndman, Brendon; Telford, Amanda; Finch, Caroline F.; Benson, Amanda C.

2012-01-01

Non-curricular avenues such as active play during school breaks have been established as a major source for children's physical and cognitive development, yet there is little information for teachers on the influences affecting primary and secondary school students' non-curricular physical activity. During this study focus groups and drawing were…

Technical activity profile and influence of body anthropometry on playing performance in female elite team handball.

PubMed

Michalsik, Lars B; Aagaard, Per; Madsen, Klavs

2015-04-01

To determine the physical demands placed on female elite team handball (TH) players in relation to playing position and body anthropometry, female elite TH primarily field players were monitored during match-play using video recording and subsequent computerized technical match analysis during 5 regular tournament match seasons. Technical match activities were distributed in 6 major types of playing actions (shots, breakthroughs, fast breaks, technical errors, defensive errors, and tackles) and further divided into various subcategories (e.g., type of shot, hard or light tackles, claspings, screenings, and blockings). Furthermore, anthropometric measurements were performed. Each player had 28.3 ± 11.0 (group means ± SD) high-intense playing actions per match with a total effective playing time of 50.70 ± 5.83 minutes. On average, each player made 2.8 ± 2.6 fast breaks, gave 7.9 ± 14.4 screenings, received 14.6 ± 9.2 tackles in total, and performed 7.7 ± 3.7 shots while in offense, along with 3.5 ± 3.8 blockings, 1.9 ± 2.7 claspings, and 6.2 ± 3.8 hard tackles in defense. Mean body height, body mass, and age in the Danish Premier Female Team Handball League were 175.4 ± 6.1 cm, 69.5 ± 6.5 kg, and 25.4 ± 3.7 years, respectively. Wing players were lighter (63.5 ± 4.8 kg, p < 0.001) and smaller (169.3 ± 4.9 cm, p < 0.001) than backcourt players (BP) (70.6 ± 5.3 kg, 177.0 ± 5.4 cm) and pivots (PV) (72.5 ± 4.9 kg, 177.7 ± 4.9 cm). In conclusion, the present match observations revealed that female elite TH players during competitive games intermittently perform a high number of short-term, high-intense technical playing actions making modern female elite TH a physically demanding team sport. No sign of technical fatigue were observed, since the amount of intense technical playing actions remained unchanged in the second half. Marked positional differences in the physical demands were demonstrated, with wing players performing more fast breaks and less physical confrontations than BP and PV. Body anthropometry differed substantially between different playing positions. Consequently, this should lead to an increase in physical training in modern female elite TH directed at specific positions and individual physical capacity.

The Effects of Spacing, Naps, and Fatigue on the Acquisition and Retention of Laparoscopic Skills.

PubMed

Spruit, Edward N; Band, Guido P H; van der Heijden, Kristiaan B; Hamming, Jaap F

Earlier research has shown that laparoscopic skills are trained more efficiently on a spaced schedule compared to a massed schedule. The aim of the study was to estimate to what extent the spacing interval, naps, and fatigue influenced the effectiveness of spacing laparoscopy training. Overall 4 groups of trainees (aged 17-41y; 72% female; N massed = 40; N break = 35; N break-nap = 37; N spaced = 37) without prior experience were trained in 3 laparoscopic tasks using a physical box trainer with different scheduling interventions. The first (massed) group received three 100-minute training sessions consecutively on a single day. The second (break) group received the sessions interrupted with two 45-minute breaks. The third (break-nap) group had the same schedule as the second group, but had two 35-minute powernap intervals during the breaks. The fourth (spaced) group had the 3 sessions on 3 consecutive days. A retention session was organized approximately 3 months after training. The results showed an overall pattern of superior performance at the end of training and at retention for the spaced group, followed by the break-nap, break, and massed group, respectively. The spaced and break-nap group significantly outperformed the break and massed group, with effect sizes ranging from 0.20 to 0.37. Spacing laparoscopic training over 3 consecutive days or weeks is superior to massed training, even if the massed training contains breaks. Breaks with sleep opportunity (i.e., lying, inactive, and muted sensory input) enhance performance over training with regular breaks and traditional massed training. Copyright © 2017 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Space-time crystals of trapped ions.

PubMed

Li, Tongcang; Gong, Zhe-Xuan; Yin, Zhang-Qi; Quan, H T; Yin, Xiaobo; Zhang, Peng; Duan, L-M; Zhang, Xiang

2012-10-19

Spontaneous symmetry breaking can lead to the formation of time crystals, as well as spatial crystals. Here we propose a space-time crystal of trapped ions and a method to realize it experimentally by confining ions in a ring-shaped trapping potential with a static magnetic field. The ions spontaneously form a spatial ring crystal due to Coulomb repulsion. This ion crystal can rotate persistently at the lowest quantum energy state in magnetic fields with fractional fluxes. The persistent rotation of trapped ions produces the temporal order, leading to the formation of a space-time crystal. We show that these space-time crystals are robust for direct experimental observation. We also study the effects of finite temperatures on the persistent rotation. The proposed space-time crystals of trapped ions provide a new dimension for exploring many-body physics and emerging properties of matter.

Gas exchange in the ice zone: the role of small waves and big animals

NASA Astrophysics Data System (ADS)

Loose, B.; Takahashi, A.; Bigdeli, A.

2016-12-01

The balance of air-sea gas exchange and net biological carbon fixation determine the transport and transformation of carbon dioxide and methane in the ocean. Air-sea gas exchange is mostly driven by upper ocean physics, but biology can also play a role. In the open ocean, gas exchange increases proportionate to the square of wind speed. When sea ice is present, this dependence breaks down in part because breaking waves and air bubble entrainment are damped out by interactions between sea ice and the wave field. At the same time, sea ice motions, formation, melt, and even sea ice-associated organisms can act to introduce turbulence and air bubbles into the upper ocean, thereby enhancing air-sea gas exchange. We take advantage of the knowledge advances of upper ocean physics including bubble dynamics to formulate a model for air-sea gas exchange in the sea ice zone. Here, we use the model to examine the role of small-scale waves and diving animals that trap air for insulation, including penguins, seals and polar bears. We compare these processes to existing parameterizations of wave and bubble dynamics in the open ocean, to observe how sea ice both mitigates and locally enhances air-sea gas transfer.

Leading isospin-breaking corrections to pion, kaon, and charmed-meson masses with twisted-mass fermions

NASA Astrophysics Data System (ADS)

Giusti, D.; Lubicz, V.; Tarantino, C.; Martinelli, G.; Sanfilippo, F.; Simula, S.; Tantalo, N.; RM123 Collaboration

2017-06-01

We present a lattice computation of the isospin-breaking corrections to pseudoscalar meson masses using the gauge configurations produced by the European Twisted Mass Collaboration with Nf=2 +1 +1 dynamical quarks at three values of the lattice spacing (a ≃0.062 , 0.082, and 0.089 fm) with pion masses in the range Mπ≃210 - 450 MeV . The strange and charm quark masses are tuned at their physical values. We adopt the RM123 method based on the combined expansion of the path integral in powers of the d - and u -quark mass difference (m^d-m^u) and of the electromagnetic coupling αe m. Within the quenched QED approximation, which neglects the effects of the sea-quark charges, and after the extrapolations to the physical pion mass and to the continuum and infinite volume limits, we provide results for the pion, kaon, and (for the first time) charmed-meson mass splittings, for the prescription-dependent parameters ɛπ0, ɛγ(M S ¯ ,2 GeV ) , ɛK0(M S ¯ ,2 GeV ) , related to the violations of the Dashen's theorem, and for the light quark mass difference (m^ d-m^ u)(M S ¯ ,2 GeV ) .

Fate of internal waves on a shallow shelf

NASA Astrophysics Data System (ADS)

Davis, Kristen; Arthur, Robert; Reid, Emma; Decarlo, Thomas; Cohen, Anne

2017-11-01

Internal waves strongly influence the physical and chemical environment of coastal ecosystems worldwide. We report novel observations from a distributed temperature sensing (DTS) system that tracked the transformation of internal waves from the shelf break to the surf zone over a shelf-slope region of a coral atoll in the South China Sea. The spatially-continuous view of the near-bottom temperature field provided by the DTS offers a perspective of physical processes previously available only in laboratory settings or numerical models. These processes include internal wave reflection off a natural slope, shoreward transport of dense fluid within trapped cores, internal ``tide pools'' (dense water left behind after the retreat of an internal wave), and internal run-down (near-bottom, offshore-directed jets of water preceding a breaking internal wave). Analysis shows that the fate of internal waves on this shelf - whether they are transmitted into shallow waters or reflected back offshore - is mediated by local water column density and shear structure, with important implications for nearshore distributions of energy, heat, and nutrients. We acknowledge the US Army Research Laboratory DoD Supercomputing Resource Center for computer time on Excalibur, which was used for the numerical simulations in this work. Funding for field work supported by Academia Sinica and for K.D. and E.R. from NSF.

ψ ( 2 S ) versus J / ψ suppression in proton-nucleus collisions from factorization violating soft color exchanges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Yan -Qing; Venugopalan, Raju; Watanabe, Kazuhiro

Here, we argue that the large suppression of themore » $$\\psi(2S)$$ inclusive cross-section relative to the $$J/\\psi$$ inclusive cross-section in proton-nucleus (p+A) collisions can be attributed to factorization breaking effects in the formation of quarkonium. These factorization breaking effects arise from soft color exchanges between charm-anticharm pairs undergoing hadronization and comoving partons that are long-lived on time scales of quarkonium formation. We compute the short distance pair production of heavy quarks in the Color Glass Condensate (CGC) effective field theory and employ an improved Color Evaporation model (ICEM) to describe their hadronization into quarkonium at large distances. The combined CGC+ICEM model provides a quantitative description of $$J/\\psi$$ and $$\\psi(2S)$$ data in proton-proton (p+p) collisions from both RHIC and the LHC. Factorization breaking effects in hadronization, due to additional parton comovers in the nucleus, are introduced heuristically by imposing a cutoff $$\\Lambda$$, representing the momentum kick from soft color exchanges, in the ICEM model. Such soft exchanges have no perceptible effect on $$J/\\psi$$ suppression in p+A collisions. In contrast, the interplay of the physics of these soft exchanges at large distances, with the physics of semi-hard rescattering at short distances, causes a significant additional suppression of $$\\psi(2S)$$ yields relative to that of the $$J/\\psi$$. A good fit of all RHIC and LHC $$J/\\psi$$ and $$\\psi(2S)$$ data, for transverse momenta $$P_\\perp\\leq 5$$ GeV in p+p and p+A collisions, is obtained for $$\\Lambda\\sim 10$$ MeV.« less

ψ ( 2 S ) versus J / ψ suppression in proton-nucleus collisions from factorization violating soft color exchanges

DOE PAGES

Ma, Yan -Qing; Venugopalan, Raju; Watanabe, Kazuhiro; ...

2018-01-31

Here, we argue that the large suppression of themore » $$\\psi(2S)$$ inclusive cross-section relative to the $$J/\\psi$$ inclusive cross-section in proton-nucleus (p+A) collisions can be attributed to factorization breaking effects in the formation of quarkonium. These factorization breaking effects arise from soft color exchanges between charm-anticharm pairs undergoing hadronization and comoving partons that are long-lived on time scales of quarkonium formation. We compute the short distance pair production of heavy quarks in the Color Glass Condensate (CGC) effective field theory and employ an improved Color Evaporation model (ICEM) to describe their hadronization into quarkonium at large distances. The combined CGC+ICEM model provides a quantitative description of $$J/\\psi$$ and $$\\psi(2S)$$ data in proton-proton (p+p) collisions from both RHIC and the LHC. Factorization breaking effects in hadronization, due to additional parton comovers in the nucleus, are introduced heuristically by imposing a cutoff $$\\Lambda$$, representing the momentum kick from soft color exchanges, in the ICEM model. Such soft exchanges have no perceptible effect on $$J/\\psi$$ suppression in p+A collisions. In contrast, the interplay of the physics of these soft exchanges at large distances, with the physics of semi-hard rescattering at short distances, causes a significant additional suppression of $$\\psi(2S)$$ yields relative to that of the $$J/\\psi$$. A good fit of all RHIC and LHC $$J/\\psi$$ and $$\\psi(2S)$$ data, for transverse momenta $$P_\\perp\\leq 5$$ GeV in p+p and p+A collisions, is obtained for $$\\Lambda\\sim 10$$ MeV.« less

A Microscopic View of Oil Slick Break-Up and Emulsion Formation in Breaking Waves

NASA Astrophysics Data System (ADS)

Law, J.; Shahrokhi, H.; Shaw, J. M.

1996-11-01

The hydrodynamic behaviour of oil spills in breaking waves determines the appropriateness and effectiveness of remedial measures during clean-up operations. Oil slicks either disperse as fine drops or form water in oil emulsions when exposed to breaking waves. However, there is little agreement with respect to the controlling variables or mechanisms for emulsification or dispersion and predictions are unreliable. For example, predicted energy dissipation rates in breaking waves are too low to account for the drop sizes encountered experimentally[1]. In this paper, we assess the impact of hydrodynamics and physical properties on the formation of dispersions or emulsions. The maximum stable drop size for dispersions arising from oil slicks and water in oil emulsions are shown to be controlled by Raleigh-Taylor instability or the prevalent local shear stress. Data from four experimental studies[2-5], with a broad range of physical properties were fitted quantitatively. As high shear events are intermittent, stable water in oil emulsions can be formed by dispersion inversion near the water air interface or by water entrained by gas bubbles passing through oil slicks. 1) Li & Garrett, 19th AMOP, Calgary AB, 1, 185-198 (1996). 2) Lin et al., Report CG-D-54-78, U.S. Coast Guard, Washington D.C. (1978). 3) Buist, MASc Thesis, University of Toronto (1979). 4) Wallace et al., 9th AMOP, Edmonton AB, 2, 421-429, June 10-12 (1986). 5) Ross Environmental Research Ltd., Ottawa ON, Report EE-96, (1987).

Maltreatment of children with disabilities: the breaking point.

PubMed

Murphy, Nancy

2011-08-01

The maltreatment of children with disabilities is a serious public health issue. Children with disabilities are 3 to 4 times more likely to be abused or neglected than are their typically developing peers. When maltreated, they are more likely to be seriously injured or harmed. As alarming as these numbers are, they likely underestimate the problem. Children with disabilities encounter all 4 types of abuse: physical, sexual, neglect, and emotional. Here, the author discusses risk factors associated with the maltreatment of children with disabilities, which, as expected, include both child and family factors.

Effect of post cure time and temperature on the properties of two phenolic-fiber composites

NASA Technical Reports Server (NTRS)

Lucy, M. H.; Price, H. L.

1975-01-01

Some effects of post-cure time and temperature on the physicomechanical properties of a phenolic-asbestos and a phenolic-glass composite are studied. The molding and post-curing procedures are discussed along with physical and mechanical test results. It is found that the specific gravity of the panels tested decreased slightly but the hardness always increased with post cure, and that the mechanical properties had different patterns of response to increasing post-cure time and temperature. For tensile properties, strength decreased, modulus increased, and elongation at break exhibited little change. In general, the phenolic-asbestos showed more positive response to post cure than did the phenolic-glass. Mold venting is found to impart better properties to the composites concerned.

Oral anatomy laboratory examinations in a physical therapy program.

PubMed

Fabrizio, Philip A

2013-01-01

The process of creating and administering traditional tagged anatomy laboratory examinations is time consuming for instructors and limits laboratory access for students. Depending on class size and the number of class, sections, creating, administering, and breaking down a tagged laboratory examination may involve one to two eight-hour days. During the time that a tagged examination is being created, student productivity may be reduced as the anatomy laboratory is inaccessible to students. Further, the type of questions that can be asked in a tagged laboratory examination may limit student assessment to lower level cognitive abilities and may limit the instructors' ability to assess the students' understanding of anatomical and clinical concepts. Anatomy is a foundational science in the Physical Therapy curriculum and a thorough understanding of anatomy is necessary to progress through the subsequent clinical courses. Physical therapy curricula have evolved to reflect the changing role of physical therapists to primary caregivers by introducing a greater scope of clinical courses earlier in the curriculum. Physical therapy students must have a thorough understanding of clinical anatomy early in the education process. However, traditional anatomy examination methods may not be reflective of the clinical thought processes required of physical therapy students. Traditional laboratory examination methods also reduce student productivity by limiting access during examination set-up and breakdown. To provide a greater complexity of questions and reduced overall laboratory time required for examinations, the Physical Therapy Program at Mercer University has introduced oral laboratory examinations for the gross anatomy course series. © 2012 American Association of Anatomists.

Effects of physical exercise training in DNA damage and repair activity in humans with different genetic polymorphisms of hOGG1 (Ser326Cys).

PubMed

Soares, Jorge Pinto; Silva, Ana Inês; Silva, Amélia M; Almeida, Vanessa; Teixeira, João Paulo; Matos, Manuela; Gaivão, Isabel; Mota, Maria Paula

2015-12-01

The main purpose of this pilot study was to investigate the possible influence of genetic polymorphisms of the hOGG1 (Ser326Cys) gene in DNA damage and repair activity by 8-oxoguanine DNA glycosylase 1 (OGG1 enzyme) in response to 16 weeks of combined physical exercise training. Thirty-two healthy Caucasian men (40-74 years old) were enrolled in this study. All the subjects were submitted to a training of 16 weeks of combined physical exercise. The subjects with Ser/Ser genotype were considered as wild-type group (WTG), and Ser/Cys and Cys/Cys genotype were analysed together as mutant group (MG). We used comet assay in conjunction with formamidopyrimidine DNA glycoslyase (FPG) to analyse both strand breaks and FPG-sensitive sites. DNA repair activity were also analysed with the comet assay technique. Our results showed no differences between DNA damage (both strand breaks and FPG-sensitive sites) and repair activity (OGG1) between genotype groups (in the pre-training condition). Regarding the possible influence of genotype in the response to 16 weeks of physical exercise training, the results revealed a decrease in DNA strand breaks in both groups, a decrease in FPG-sensitive sites and an increase in total antioxidant capacity in the WTG, but no changes were found in MG. No significant changes in DNA repair activity was observed in both genotype groups with physical exercise training. This preliminary study suggests the possibility of different responses in DNA damage to the physical exercise training, considering the hOGG1 Ser326Cys polymorphism. Copyright © 2015 John Wiley & Sons, Ltd.

Physics reach of MoEDAL at LHC: magnetic monopoles, supersymmetry and beyond

NASA Astrophysics Data System (ADS)

Mavromatos, Nick E.; Mitsou, Vasiliki A.

2017-12-01

MoEDAL is a pioneering experiment designed to search for highly ionising messengers of new physics such as magnetic monopoles or massive (pseudo-)stable charged particles, that are predicted to exist in a plethora of models beyond the Standard Model. Its ground-breaking physics program defines a number of scenarios that yield potentially revolutionary insights into such foundational questions as, are there extra dimensions or new symmetries, what is the mechanism for the generation of mass, does magnetic charge exist, what is the nature of dark matter, and, how did the big-bang develop at the earliest times. MoEDAL's purpose is to meet such far-reaching challenges at the frontier of the field. The physics reach of the existing MoEDAL detector is discussed, giving emphasis on searches for magnetic monopoles, supersymmetric (semi)stable partners, doubly charged Higgs bosons, and exotic structures such as black-hole remnants in models with large extra spatial dimensions and D-matter in some brane theories.

Breaking Lorentz reciprocity to overcome the time-bandwidth limit in physics and engineering.

PubMed

Tsakmakidis, K L; Shen, L; Schulz, S A; Zheng, X; Upham, J; Deng, X; Altug, H; Vakakis, A F; Boyd, R W

2017-06-23

A century-old tenet in physics and engineering asserts that any type of system, having bandwidth Δω, can interact with a wave over only a constrained time period Δ t inversely proportional to the bandwidth (Δ t ·Δω ~ 2π). This law severely limits the generic capabilities of all types of resonant and wave-guiding systems in photonics, cavity quantum electrodynamics and optomechanics, acoustics, continuum mechanics, and atomic and optical physics but is thought to be completely fundamental, arising from basic Fourier reciprocity. We propose that this "fundamental" limit can be overcome in systems where Lorentz reciprocity is broken. As a system becomes more asymmetric in its transport properties, the degree to which the limit can be surpassed becomes greater. By way of example, we theoretically demonstrate how, in an astutely designed magnetized semiconductor heterostructure, the above limit can be exceeded by orders of magnitude by using realistic material parameters. Our findings revise prevailing paradigms for linear, time-invariant resonant systems, challenging the doctrine that high-quality resonances must invariably be narrowband and providing the possibility of developing devices with unprecedentedly high time-bandwidth performance. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Why Older Adults Spend Time Sedentary and Break Their Sedentary Behavior: A Mixed-Methods Approach Using Life-Logging Equipment.

PubMed

Dontje, Manon L; Leask, Calum F; Harvey, Juliet; Skelton, Dawn A; Chastin, Sebastien F M

2018-04-01

Older adults are recommended to reduce their sedentary time to promote healthy ageing. To develop effective interventions identifying when, why, and how older adults are able to change their sitting habits is important. The aim of this mixed-method study was to improve our understanding of reasons for (breaking) sedentary behavior in older adults. Thirty older adults (74.0 [±5.3] years old, 73% women) were asked about their believed reasons for (breaking) sedentary behavior, and about their actual reasons when looking at a personal storyboard with objective records of activPAL monitor data and time-lapse camera pictures showing all their periods of sedentary time in a day. The most often mentioned believed reason for remaining sedentary was television/radio (mentioned by 48.3%), while eating/drinking was most often mentioned as actual reason (96.6%). Only 17.2% believed that food/tea preparation was a reason to break up sitting, while this was an actual reason for 82.8% of the study sample. Results of this study show that there is a discrepancy between believed and actual reasons for (breaking) sedentary behavior. These findings suggest developing interventions utilizing the actual reasons for breaking sedentary behavior to reduce sedentary time in older adults.

Exact PsTd invariant and PsTd symmetric breaking solutions, symmetry reductions and Bäcklund transformations for an AB-KdV system

NASA Astrophysics Data System (ADS)

Jia, Man; Lou, Sen Yue

2018-05-01

In natural and social science, many events happened at different space-times may be closely correlated. Two events, A (Alice) and B (Bob) are defined as correlated if one event is determined by another, say, B = f ˆ A for suitable f ˆ operators. A nonlocal AB-KdV system with shifted-parity (Ps, parity with a shift), delayed time reversal (Td, time reversal with a delay) symmetry where B =Ps ˆ Td ˆ A is constructed directly from the normal KdV equation to describe two-area physical event. The exact solutions of the AB-KdV system, including PsTd invariant and PsTd symmetric breaking solutions are shown by different methods. The PsTd invariant solution show that the event happened at A will happen also at B. These solutions, such as single soliton solutions, infinitely many singular soliton solutions, soliton-cnoidal wave interaction solutions, and symmetry reduction solutions etc., show the AB-KdV system possesses rich structures. Also, a special Bäcklund transformation related to residual symmetry is presented via the localization of the residual symmetry to find interaction solutions between the solitons and other types of the AB-KdV system.

8 CFR 1240.64 - Eligibility-general.

Code of Federal Regulations, 2010 CFR

2010-01-01

....64 Aliens and Nationality EXECUTIVE OFFICE FOR IMMIGRATION REVIEW, DEPARTMENT OF JUSTICE IMMIGRATION... of continuous physical presence and certain breaks in presence. For purposes of calculating continuous physical presence under this section, section 309(c)(5)(A) of IIRIRA and section 240A(d)(1) of the...

Non-Kolmogorovian Approach to the Context-Dependent Systems Breaking the Classical Probability Law

NASA Astrophysics Data System (ADS)

Asano, Masanari; Basieva, Irina; Khrennikov, Andrei; Ohya, Masanori; Yamato, Ichiro

2013-07-01

There exist several phenomena breaking the classical probability laws. The systems related to such phenomena are context-dependent, so that they are adaptive to other systems. In this paper, we present a new mathematical formalism to compute the joint probability distribution for two event-systems by using concepts of the adaptive dynamics and quantum information theory, e.g., quantum channels and liftings. In physics the basic example of the context-dependent phenomena is the famous double-slit experiment. Recently similar examples have been found in biological and psychological sciences. Our approach is an extension of traditional quantum probability theory, and it is general enough to describe aforementioned contextual phenomena outside of quantum physics.

Defining Nitrogen Kinetics for Air Break in Prebreathe

NASA Technical Reports Server (NTRS)

Conkin, Johnny

2009-01-01

Actual tissue nitrogen (N2) kinetics are complex; the uptake and elimination is often approximated with a single half-time compartment in statistical descriptions of denitrogenation [prebreathe (PB)] protocols. Air breaks during PB complicate N2 kinetics. A comparison of symmetrical versus asymmetrical N2 kinetics was performed using the time to onset of hypobaric decompression sickness (DCS) as a surrogate for actual venous N2 tension. Published results of 12 tests involving 179 hypobaric exposures in altitude chambers after PB, with and without air breaks, provide the complex protocols from which to model N2 kinetics. DCS survival time for combined control and air breaks were described with an accelerated log logistic model where N2 uptake and elimination before, during, and after the air break was computed with a simple exponential function or a function that changed half-time depending on ambient N2 partial pressure. P1N2-P2 = delta P defined DCS dose for each altitude exposure, where P2 was the test altitude and P1N2 was computed N2 pressure at the beginning of the altitude exposure. The log likelihood (LL) without DCS dose (null model) was -155.6, and improved (best-fit) to -97.2 when dose was defined with a 240 min half-time for both N2 elimination and uptake during the PB. The description of DCS survival time was less precise with asymmetrical N2 kinetics, for example, LL was -98.9 with 240 min half-time elimination and 120 min half-time uptake. The statistical regression described survival time mechanistically linked to symmetrical N2 kinetics during PBs that also included air breaks. The results are data-specific, and additional data may change the conclusion. The regression is useful to compute additional PB time to compensate for an air break in PB within the narrow range of tested conditions.

Give me a better break: Choosing workday break activities to maximize resource recovery.

PubMed

Hunter, Emily M; Wu, Cindy

2016-02-01

Surprisingly little research investigates employee breaks at work, and even less research provides prescriptive suggestions for better workday breaks in terms of when, where, and how break activities are most beneficial. Based on the effort-recovery model and using experience sampling methodology, we examined the characteristics of employee workday breaks with 95 employees across 5 workdays. In addition, we examined resources as a mediator between break characteristics and well-being. Multilevel analysis results indicated that activities that were preferred and earlier in the work shift related to more resource recovery following the break. We also found that resources mediated the influence of preferred break activities and time of break on health symptoms and that resource recovery benefited person-level outcomes of emotional exhaustion, job satisfaction, and organizational citizenship behavior. Finally, break length interacted with the number of breaks per day such that longer breaks and frequent short breaks were associated with more resources than infrequent short breaks. (c) 2016 APA, all rights reserved).

Time and space: undergraduate Mexican physics in motion

NASA Astrophysics Data System (ADS)

Candela, Antonia

2010-09-01

This is an ethnographic study of the trajectories and itineraries of undergraduate physics students at a Mexican university. In this work learning is understood as being able to move oneself and, other things (cultural tools), through the space-time networks of a discipline (Nespor in Knowledge in motion: space, time and curriculum in undergraduate physics and management. Routledge Farmer, London, 1994). The potential of this socio-cultural perspective allows an analysis of how students are connected through extended spaces and times with an international core discipline as well as with cultural features related to local networks of power and construction. Through an example, I show that, from an actor-network-theory (Latour in Science in action. Harvard University Press, Cambridge, 1987), that in order to understand the complexities of undergraduate physics processes of learning you have to break classroom walls and take into account students' movements through complex spatial and temporal traces of the discipline of physics. Mexican professors do not give classes following one textbook but in a moment-to-moment open dynamism tending to include undergraduate students as actors in classroom events extending the teaching space-time of the classroom to the disciplinary research work of physics. I also find that Mexican undergraduate students show initiative and display some autonomy and power in the construction of their itineraries as they are encouraged to examine a variety of sources including contemporary research articles, unsolved physics problems, and even to participate in several physicists' spaces, as for example being speakers at the national congresses of physics. Their itineraries also open up new spaces of cultural and social practices, creating more extensive networks beyond those associated with a discipline. Some economic, historical and cultural contextual features of this school of sciences are analyzed in order to help understanding the particular way students are encouraged to develop their autonomy.

The Influence of Break Timing on the Sleep Quantity and Quality of Fly-in, Fly-out Shiftworkers

PubMed Central

PAECH, Gemma M.; FERGUSON, Sally A.; BANKS, Siobhan; DORRIAN, Jillian; ROACH, Gregory D.

2014-01-01

Although shift and break timing is known to affect the sleep of shiftworkers, this has not been demonstrated in Fly-in, Fly-out (FIFO) settings which, compared to residential based settings, may be favourable for sleep. This study investigated the sleep quantity and quality of shiftworkers working a FIFO operation comprising of shifts, and therefore breaks, across the 24-h day. The sleep of 24 males (50.43 ± 8.57 yr) was measured using actigraphy and sleep diaries. Morning breaks were associated with less sleep (09:00–12:00 h; 4.4 ± 1.3 h) and a poorer sleep quality (06:00–09:00 h; 3.1 ± 1.0, “average”) compared to breaks beginning between 00:00 h and 03:00 h (6.8 ± 1.7 h; 2.2 ± 0.9, “good”). Sleep efficiency remained constant regardless of break timing (85.9 ± 5.0% to 89.9 ± 3.5%). Results indicate that even in operations such as FIFO where sleeping conditions are near-optimal and the break duration is held constant, the influence of the endogenous circadian pacemaker on sleep duration is evident. PMID:25224336

Planck 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-06-02

Planck 2010 From the Planck Scale to the ElectroWeak Scale The conference will be the twelfth one in a series of meetings on physics beyond the Standard Model, organized jointly by several European groups: Bonn, CERN, Ecole Polytechnique, ICTP, Madrid, Oxford, Padua, Pisa, SISSA and Warsaw as part of activities in the framework of the European network UNILHC.Topics to be discussed: Supersymmetry Supergravity & string phenomenology Extra dimensions Electroweak symmetry breaking LHC and Tevatron Physics Collider physics Flavor & neutrinos physics Astroparticle & cosmology Gravity & holography Strongly coupled physics & CFT Registration: registration will be open until May 1st.more » Registration fees amount to 150 CHF and cover the cost of the coffee breaks and the social dinner. Payment has to be made online. The deadline for registration has been postponed to May 7th. However, after May 3th, we shall not accept any talk request any more. The meeting will be partly supported by ° the Marie Curie Initial Training Network "UNILHC" PITN-GA-2009-23792, ° the ERC Advanced Grant "MassTeV" 226371, ° and the CERN-TH unit.« less

Planck 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Covi, Laura; Hasenkamp, J.

2010-06-02

Planck 2010 From the Planck Scale to the ElectroWeak Scale The conference will be the twelfth one in a series of meetings on physics beyond the Standard Model, organized jointly by several European groups: Bonn, CERN, Ecole Polytechnique, ICTP, Madrid, Oxford, Padua, Pisa, SISSA and Warsaw as part of activities in the framework of the European network UNILHC.Topics to be discussed: Supersymmetry Supergravity & string phenomenology. Extra dimensions; Electroweak symmetry breaking; LHC and Tevatron Physics; Collider physics; Flavor & neutrinos physics Astroparticle & cosmology; Gravity & holography; BStrongly coupled physics & CFT. Registration: registration will be open until May 1st.more » Registration fees amount to 150 CHF and cover the cost of the coffee breaks and the social dinner. Payment has to be made online. The deadline for registration has been postponed to May 7th. However, after May 3th, we shall not accept any talk request any more. The meeting will be partly supported by; the Marie Curie Initial Training Network UNILHC PITN-GA-2009-23792; the ERC Advanced Grant "MassTeV" 226371; and the CERN-TH unit.« less

Planck 2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murayama, Hitoshi

2010-06-02

Planck 2010 From the Planck Scale to the ElectroWeak Scale The conference will be the twelfth one in a series of meetings on physics beyond the Standard Model, organized jointly by several European groups: Bonn, CERN, Ecole Polytechnique, ICTP, Madrid, Oxford, Padua, Pisa, SISSA and Warsaw as part of activities in the framework of the European network UNILHC.Topics to be discussed: SupersymmetrySupergravity & string phenomenology Extra dimensions Electroweak symmetry breaking LHC and Tevatron Physics Collider physics Flavor & neutrinos physics Astroparticle & cosmology Gravity & holography Strongly coupled physics & CFT Registration: registration will be open until May 1st. Registrationmore » fees amount to 150 CHF and cover the cost of the coffee breaks and the social dinner. Payment has to be made online. The deadline for registration has been postponed to May 7th. However, after May 3th, we shall not accept any talk request any more. The meeting will be partly supported by; the Marie Curie Initial Training Network "UNILHC" PITN-GA-2009-23792, the ERC Advanced Grant "MassTeV" 226371, and the CERN-TH unit.« less

The Relation between Popularity and Aggressive, Destructive, and Norm-Breaking Behaviors: Moderating Effects of Athletic Abilities, Physical Attractiveness, and Prosociality

ERIC Educational Resources Information Center

Dijkstra, Jan Kornelis; Lindenberg, Siegwart; Verhulst, Frank C.; Ormel, Johan; Veenstra, Rene

2009-01-01

The aim of this study was to examine the relations between popularity and different types of aggressive, destructive, and norm-breaking behaviors in a large cross-sectional sample of adolescents (N=3,312, M age=13.60). We were interested in the extent to which the relations of these behaviors with popularity were moderated by positive features…

Breaking time reversal in a simple smooth chaotic system.

PubMed

Tomsovic, Steven; Ullmo, Denis; Nagano, Tatsuro

2003-06-01

Within random matrix theory, the statistics of the eigensolutions depend fundamentally on the presence (or absence) of time reversal symmetry. Accepting the Bohigas-Giannoni-Schmit conjecture, this statement extends to quantum systems with chaotic classical analogs. For practical reasons, much of the supporting numerical studies of symmetry breaking have been done with billiards or maps, and little with simple, smooth systems. There are two main difficulties in attempting to break time reversal invariance in a continuous time system with a smooth potential. The first is avoiding false time reversal breaking. The second is locating a parameter regime in which the symmetry breaking is strong enough to transform the fluctuation properties fully to the broken symmetry case, and yet remain weak enough so as not to regularize the dynamics sufficiently that the system is no longer chaotic. We give an example of a system of two coupled quartic oscillators whose energy level statistics closely match with those of the Gaussian unitary ensemble, and which possesses only a minor proportion of regular motion in its phase space.

The Impact of School Breaks on Students Living in Poverty

ERIC Educational Resources Information Center

McDonald, Michelle

2013-01-01

Summer and winter breaks from school can be highly anticipated times for students and educators. However, for students living in poverty, the break from school can bring hidden challenges that school psychologists should be aware of when preparing for vacation. Research has shown that school breaks affect students from varying socioeconomic status…

Spin-rotation symmetry breaking and triplet superconducting state in doped topological insulator CuxBi2Se3

NASA Astrophysics Data System (ADS)

Zheng, Guo-Qing

Spontaneous symmetry breaking is an important concept for understanding physics ranging from the elementary particles to states of matter. For example, the superconducting state breaks global gauge symmetry, and unconventional superconductors can break additional symmetries. In particular, spin rotational symmetry is expected to be broken in spin-triplet superconductors. However, experimental evidence for such symmetry breaking has not been obtained so far in any candidate compounds. We report 77Se nuclear magnetic resonance measurements which showed that spin rotation symmetry is spontaneously broken in the hexagonal plane of the electron-doped topological insulator Cu0.3Bi2Se3 below the superconducting transition temperature Tc =3.4 K. Our results not only establish spin-triplet (odd parity) superconductivity in this compound, but also serve to lay a foundation for the research of topological superconductivity (Ref.). We will also report the doping mechanism and superconductivity in Sn1-xInxTe.

Nontrivial Berry phase in magnetic BaMnSb2 semimetal

PubMed Central

Huang, Silu; Shelton, W. A.; Plummer, E. W.; Jin, Rongying

2017-01-01

The subject of topological materials has attracted immense attention in condensed-matter physics because they host new quantum states of matter containing Dirac, Majorana, or Weyl fermions. Although Majorana fermions can only exist on the surface of topological superconductors, Dirac and Weyl fermions can be realized in both 2D and 3D materials. The latter are semimetals with Dirac/Weyl cones either not tilted (type I) or tilted (type II). Although both Dirac and Weyl fermions have massless nature with the nontrivial Berry phase, the formation of Weyl fermions in 3D semimetals require either time-reversal or inversion symmetry breaking to lift degeneracy at Dirac points. Here we demonstrate experimentally that canted antiferromagnetic BaMnSb2 is a 3D Weyl semimetal with a 2D electronic structure. The Shubnikov–de Hass oscillations of the magnetoresistance give nearly zero effective mass with high mobility and the nontrivial Berry phase. The ordered magnetic arrangement (ferromagnetic ordering in the ab plane and antiferromagnetic ordering along the c axis below 286 K) breaks the time-reversal symmetry, thus offering us an ideal platform to study magnetic Weyl fermions in a centrosymmetric material. PMID:28539436

21 CFR 600.11 - Physical establishment, equipment, animals, and care.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 7 2011-04-01 2010-04-01 true Physical establishment, equipment, animals, and... designed and constructed to permit thorough cleaning and, where possible, inspection for cleanliness. All... each culture is designed to withstand handling without breaking. (3) Work with spore-forming...

The practice of active rest by workplace units improves personal relationships, mental health, and physical activity among workers.

PubMed

Michishita, Ryoma; Jiang, Ying; Ariyoshi, Daisuke; Yoshida, Marie; Moriyama, Hideko; Yamato, Hiroshi

2017-03-28

This study was designed to clarify the effects of active rest, with a focus on the practice of short-time group exercise by workplace units, on personal relationships, mental health, physical activity, and work ability among workers. Fifty-nine white-collar workers (40 males and 19 females) performed our active rest (short-time exercise) program, which consists of warm-up, cognitive functional training, aerobic exercise, resistance training and cool-down for 10 minutes per day, 3 times per week during their lunch breaks for 10 weeks. Participants from a workplace unit were randomly allocated to the intervention (five workplaces, n=29) or control groups (six workplaces, n=30). The participants' anthropometric measurements, and their Profile of Mood States (POMS) 2, Brief Job Stress Questionnaire (BJSQ), physical activity levels and Work Ability Index were examined at the baseline and after the 10-week intervention. After 10 weeks, physical activity levels, especially the time spent in moderate and vigorous intensity, increased in the intervention group (p<0.05). The items of "vigor-activity" and "friendliness" improved in POMS 2, while "vigor," "interpersonal stress," "support from superiors, colleagues, and family/friends," and "job satisfaction" improved in BJSQ in the intervention group (p<0.05). In the intervention group, the number of exercise participation was positively correlated with the change in "vigor-activity" in POMS 2 (r=0.467, p=0.011). These results suggest that the practice of active rest by workplace units is important for improving personal relationships, mental health, and physical activity among workers.

The practice of active rest by workplace units improves personal relationships, mental health, and physical activity among workers

PubMed Central

Michishita, Ryoma; Jiang, Ying; Ariyoshi, Daisuke; Yoshida, Marie; Moriyama, Hideko; Yamato, Hiroshi

2016-01-01

Aim: This study was designed to clarify the effects of active rest, with a focus on the practice of short-time group exercise by workplace units, on personal relationships, mental health, physical activity, and work ability among workers. Methods: Fifty-nine white-collar workers (40 males and 19 females) performed our active rest (short-time exercise) program, which consists of warm-up, cognitive functional training, aerobic exercise, resistance training and cool-down for 10 minutes per day, 3 times per week during their lunch breaks for 10 weeks. Participants from a workplace unit were randomly allocated to the intervention (five workplaces, n=29) or control groups (six workplaces, n=30). The participants' anthropometric measurements, and their Profile of Mood States (POMS) 2, Brief Job Stress Questionnaire (BJSQ), physical activity levels and Work Ability Index were examined at the baseline and after the 10-week intervention. Results: After 10 weeks, physical activity levels, especially the time spent in moderate and vigorous intensity, increased in the intervention group (p<0.05). The items of "vigor-activity" and "friendliness" improved in POMS 2, while "vigor," "interpersonal stress," "support from superiors, colleagues, and family/friends," and "job satisfaction" improved in BJSQ in the intervention group (p<0.05). In the intervention group, the number of exercise participation was positively correlated with the change in "vigor-activity" in POMS 2 (r=0.467, p=0.011). Conclusions: These results suggest that the practice of active rest by workplace units is important for improving personal relationships, mental health, and physical activity among workers. PMID:27980249

New structures of power density spectra for four Kepler active galactic nuclei

NASA Astrophysics Data System (ADS)

Dobrotka, A.; Antonuccio-Delogu, V.; Bajčičáková, I.

2017-09-01

Many nearby active galactic nuclei display a significant short-term variability. In this work, we reanalyse photometric data of four active galactic nuclei observed by Kepler in order to study the flickering activity, with our main goal to search for multiple components in the power density spectra. We find that all four objects have similar characteristics, with two break frequencies at approximately log( f /Hz) = -5.2 and -4.7. We consider some physical phenomena whose characteristic time-scales are consistent with those observed, in particular mass accretion fluctuations in the inner geometrically thick disc (hot X-ray corona) and unstable relativistic Rayleigh-Taylor modes. The former is supported by detection of the same break frequencies in the Swift X-ray data of ZW229-15. We also discuss rms-flux relations, and we detect a possible typical linear trend at lower flux levels. Our findings support the hypothesis of a multiplicative character of variability, in agreement with the propagating accretion fluctuation model.

Dynamics of associative polymer solutions: Capillary break-up, jetting and rheology

NASA Astrophysics Data System (ADS)

Sharma, Vivek; Serdy, James G.; Threfall-Holmes, Phil; McKinley, Gareth H.

2011-11-01

Associative polymer solutions are used in extensively in the formulations for water-borne paints, food, inks, cosmetics, etc to control the rheology and processing behavior of multi-component dispersions. These complex dispersions are processed and used over a broad range of shear and extensional rates. Furthermore, the commercially relevant formulations use dilute solutions of associative polymers, which have low viscosity and short relaxation times, and hence their non-Newtonian response is not apparent in a conventional rheometer. In this talk, we explore several methods for systematically exploring the linear and nonlinear solution rheology of associative polymer dispersions, including: fractional model description of physical gelation, high frequency oscillatory tests at frequencies up to 10 kHz, microfluidic shear rheometry at deformation rates up to 1000000 /s and the influence of transient extensional rheology in the jet breakup. We show that high deformation rates can be obtained in jetting flows, and the growth and evolution of instability during jetting and break-up of these viscoelastic fluids shows the influence of both elasticity and extensibility.

Two symmetry-breaking mechanisms for the development of orientation selectivity in a neural system

NASA Astrophysics Data System (ADS)

Cho, Myoung Won; Chun, Min Young

2015-11-01

Orientation selectivity is a remarkable feature of the neurons located in the primary visual cortex. Provided that the visual neurons acquire orientation selectivity through activity-dependent Hebbian learning, the development process could be understood as a kind of symmetry-breaking phenomenon in the view of physics. This paper examines the key mechanisms of the orientation selectivity development process. Be found that at least two different mechanisms, which lead to the development of orientation selectivity by breaking the radial symmetry in receptive fields. The first is a simultaneous symmetry-breaking mechanism occurring based on the competition between neighboring neurons, and the second is a spontaneous one occurring based on the nonlinearity in interactions. Only the second mechanism leads to the formation of a columnar pattern whose characteristics is in accord with those observed in an animal experiment.

Mechanical break junctions: enormous information in a nanoscale package.

PubMed

Natelson, Douglas

2012-04-24

Mechanical break junctions, particularly those in which a metal tip is repeatedly moved in and out of contact with a metal film, have provided many insights into electronic conduction at the atomic and molecular scale, most often by averaging over many possible junction configurations. This averaging throws away a great deal of information, and Makk et al. in this issue of ACS Nano demonstrate that, with both simulated and real experimental data, more sophisticated two-dimensional analysis methods can reveal information otherwise obscured in simple histograms. As additional measured quantities come into play in break junction experiments, including thermopower, noise, and optical response, these more sophisticated analytic approaches are likely to become even more powerful. While break junctions are not directly practical for useful electronic devices, they are incredibly valuable tools for unraveling the electronic transport physics relevant for ultrascaled nanoelectronics.

QUANTITATION OF INTRACELLULAR NAD(P)H IN LIVING CELLS CAN MONITOR AN IMBALANCE OF DNA SINGLE STRAND BREAK REPAIR IN REAL TIME

EPA Science Inventory

Quantitation of intracellular NAD(P)H in living cells can monitor an imbalance of DNA single strand break repair in real time.

ABSTRACT

DNA single strand breaks (SSBs) are one of the most frequent DNA lesions in genomic DNA generated either by oxidative stress or du...

Dynamics of Galaxies

NASA Astrophysics Data System (ADS)

Bertin, Giuseppe

2000-08-01

Part I. Basic Phenomenology: 1. Scales; 2. Observational windows; 3. Classifications; 4. Photometry, kinematics, dark matter; 5. Basic questions, semi-empirical approach, dynamical window; Part II. Physical Models: 6. Self-gravity and relation with plasma physics; 7. Relaxation times, absence of thermodynamical equilibrium; 8. Models; 9. Equilibrium and stability: symmetry and symmetry breaking; 10. Classical ellipsoids; 11. Introduction to dispersive waves; 12. Jeans instability; Part III. Spiral Galaxies: 13. Orbits; 14. The basic state: vertical and horizontal equilibrium in the disk; 15. Density waves; 16. Role of gas; 17. Global spiral modes; 18. Spiral structure in galaxies; 19. Bending waves; 20. Dark matter in spiral galaxies; Part IV. Elliptical Galaxies: 21. Orbits; 22. Stellar dynamical approach; 23. Stability; 24. Dark matter in elliptical galaxies; Part V. In Perspective: 25. Selected aspects of formation and evolution; Notes; Index.

Instant Recess®: a practical tool for increasing physical activity during the school day.

PubMed

Whitt-Glover, Melicia C; Ham, Sandra A; Yancey, Antronette K

2011-01-01

An increased prevalence of overweight/obesity among children has led to school district level policies to increase physical activity (PA) among elementary school students. Interventions are needed that increase activity levels without sacrificing time spent in academics. We evaluated a policy implementation intervention for to increase in-school PA in elementary schools in Forsyth County, North Carolina, in a randomized study with a delayed intervention control group. The study included third- through fifth-grade classrooms in eight elementary schools. Instant Recess® was used to introduce 10-minute PA breaks in classrooms on schedules determined by teachers. Direct observation was used to measure activity levels, other student behaviors, and teacher behaviors related to PA in the classrooms. Twenty-eight visits to schools were made during the spring and fall semesters of 2009. At baseline 11% to 44% of intervention and control schools were engaged in classroom-based PA. PA increased from baseline to spring follow-up in intervention schools and was maintained the following fall. Control schools decreased PA from baseline to spring and increased PA once they began the intervention. Students in classrooms engaged in Instant Recess exhibited statistically significant increases in light (51%) and moderate-intensity (16%) PA and increases in time spent in on-task behavior (11%). Control schools experienced similar benefits after they began implementing Instant Recess. Instant Recess is useful for increasing PA and improving behavior among elementary school children. Additional research may be needed to understand how to create policies supporting classroom activity breaks and how to assess policy adherence.

Evaluating crude oil chemical dispersion efficacy in a flow-through wave tank under regular non-breaking wave and breaking wave conditions.

PubMed

Li, Zhengkai; Lee, Kenneth; King, Thomas; Boufadel, Michel C; Venosa, Albert D

2009-05-01

Testing dispersant effectiveness under conditions similar to that of the open environment is required for improvements in operational procedures and the formulation of regulatory guidelines. To this end, a novel wave tank facility was fabricated to study the dispersion of crude oil under regular non-breaking and irregular breaking wave conditions. This wave tank facility was designed for operation in a flow-through mode to simulate both wave- and current-driven hydrodynamic conditions. We report here an evaluation of the effectiveness of chemical dispersants (Corexit EC9500A and SPC 1000) on two crude oils (Medium South American [MESA] and Alaska North Slope [ANS]) under two different wave conditions (regular non-breaking and plunging breaking waves) in this wave tank. The dispersant effectiveness was assessed by measuring the water column oil concentration and dispersed oil droplet size distribution. In the absence of dispersants, nearly 8-19% of the test crude oils were dispersed and diluted under regular wave and breaking wave conditions. In the presence of dispersants, about 21-36% of the crude oils were dispersed and diluted under regular waves, and 42-62% under breaking waves. Consistently, physical dispersion under regular waves produced large oil droplets (volumetric mean diameter or VMD > or = 300 microm), whereas chemical dispersion under breaking waves created small droplets (VMD < or = 50 microm). The data can provide useful information for developing better operational guidelines for dispersant use and improved predictive models on dispersant effectiveness in the field.

Impacts of a lengthening open water season on Alaskan coastal communities: deriving locally relevant indices from large-scale datasets and community observations

NASA Astrophysics Data System (ADS)

Rolph, Rebecca J.; Mahoney, Andrew R.; Walsh, John; Loring, Philip A.

2018-05-01

Using thresholds of physical climate variables developed from community observations, together with two large-scale datasets, we have produced local indices directly relevant to the impacts of a reduced sea ice cover on Alaska coastal communities. The indices include the number of false freeze-ups defined by transient exceedances of ice concentration prior to a corresponding exceedance that persists, false break-ups, timing of freeze-up and break-up, length of the open water duration, number of days when the winds preclude hunting via boat (wind speed threshold exceedances), the number of wind events conducive to geomorphological work or damage to infrastructure from ocean waves, and the number of these wind events with on- and along-shore components promoting water setup along the coastline. We demonstrate how community observations can inform use of large-scale datasets to derive these locally relevant indices. The two primary large-scale datasets are the Historical Sea Ice Atlas for Alaska and the atmospheric output from a regional climate model used to downscale the ERA-Interim atmospheric reanalysis. We illustrate the variability and trends of these indices by application to the rural Alaska communities of Kotzebue, Shishmaref, and Utqiaġvik (previously Barrow), although the same procedure and metrics can be applied to other coastal communities. Over the 1979-2014 time period, there has been a marked increase in the number of combined false freeze-ups and false break-ups as well as the number of days too windy for hunting via boat for all three communities, especially Utqiaġvik. At Utqiaġvik, there has been an approximate tripling of the number of wind events conducive to coastline erosion from 1979 to 2014. We have also found a delay in freeze-up and earlier break-up, leading to a lengthened open water period for all of the communities examined.

Ocean Surface Wave Optical Roughness - Innovative Measurement and Modeling

DTIC Science & Technology

2008-01-01

e.g. Jessup and Phadnis , 2005) have been reported. Our effort seeks to provide a more comprehensive description of the physical and optical roughness...1986: Statistics of breaking waves observed as whitecaps in the open sea, Journal of Physical Oceanography, 16, 290-297. Jessup, A.T. and Phadnis

Long-time Dynamics of Stochastic Wave Breaking

NASA Astrophysics Data System (ADS)

Restrepo, J. M.; Ramirez, J. M.; Deike, L.; Melville, K.

2017-12-01

A stochastic parametrization is proposed for the dynamics of wave breaking of progressive water waves. The model is shown to agree with transport estimates, derived from the Lagrangian path of fluid parcels. These trajectories are obtained numerically and are shown to agree well with theory in the non-breaking regime. Of special interest is the impact of wave breaking on transport, momentum exchanges and energy dissipation, as well as dispersion of trajectories. The proposed model, ensemble averaged to larger time scales, is compared to ensemble averages of the numerically generated parcel dynamics, and is then used to capture energy dissipation and path dispersion.

PREFACE: XXV International Conference on Photonic, Electronic and Atomic Collisions

NASA Astrophysics Data System (ADS)

Becker, Uwe; Moshammer, Robert; Mokler, Paul; Ullrich, Joachim

2007-07-01

The XXVth ICPEAC in Freiburg marked a notable anniversary in collision physics: half a century ago the first conference in the series of International Conferences on the Physics of Electronic and Atomic Collisions (ICPEAC) was held in New York (1958). Since then, the development of electronic and atomic collision physics has seen tremendous progress. Starting during a time, when this field was regarded as somehow out-of-date, certainly not being in the main stream compared to particle and high-energy physics, it has expanded in a rather exceptional and unforeseen way. Over the years the original scope on electronic, atomic and heavy-ion collision physics was extended substantially to include upcoming expanding fields like synchrotron-radiation and strong-field laser-based atomic and molecular physics giving rise to a change of name to 'Photonic', Electronic and Atomic Collisions (ICPEAC) being used for the first time for the ICPEAC in Santa Fee in 2001. Nowadays, the ICPEAC has opened its agenda even more widely to other fields of atomic and molecular physics, such as interactions with clusters, bio-molecules and surfaces, to cold collisions, coherent control, femto- and attosecond physics and, with the Freiburg conference, to the application of free-electron lasers in the vacuum ultraviolet and soft x-ray regime, a field of potentially huge future impact in essentially all areas of science. In this larger context the XXVth ICPEAC in Freiburg with more than 800 participants set new standards. Representatives from all fields of Atomic, Molecular and Photon-based science came together and had very fruitful, inter-disciplinary discussions. This new forum of collision-based AMP physics will serve as a showcase example of future conferences, bridging not only the gap between different fields of collision physics but also, equally important, between different continents and cultures. The next ICPEAC is going to take place in Kalamazoo in North America, the one after that in Belfast back in Europe, and the subsequent one, 2013 in Lanzhou, will be the first one ever held in China. A great perspective for this ever-growing field of science! Uwe Becker (Fritz-Haber-Institut, Berlin) Robert Moshammer (Max-Planck-Institut für Kernphysik, Heidelberg) Paul Mokler (Gesellschaft für Schwerionenforschung, Darmstadt) Joachim Ullrich (Max-Planck-Institut für Kernphysik, Heidelberg) Editors Relaxed atmosphere for discussions during coffee breaks at ICPEAC XXV in Freiburg. The PDF file contains details of previous conferences, sponsors, exhibitors and committees.

Quantum break-time of de Sitter

NASA Astrophysics Data System (ADS)

Dvali, Gia; Gómez, César; Zell, Sebastian

2017-06-01

The quantum break-time of a system is the time-scale after which its true quantum evolution departs from the classical mean field evolution. For capturing it, a quantum resolution of the classical background—e.g., in terms of a coherent state—is required. In this paper, we first consider a simple scalar model with anharmonic oscillations and derive its quantum break-time. Next, following [1], we apply these ideas to de Sitter space. We formulate a simple model of a spin-2 field, which for some time reproduces the de Sitter metric and simultaneously allows for its well-defined representation as quantum coherent state of gravitons. The mean occupation number N of background gravitons turns out to be equal to the de Sitter horizon area in Planck units, while their frequency is given by the de Sitter Hubble parameter. In the semi-classical limit, we show that the model reproduces all the known properties of de Sitter, such as the redshift of probe particles and thermal Gibbons-Hawking radiation, all in the language of quantum S-matrix scatterings and decays of coherent state gravitons. Most importantly, this framework allows to capture the 1/N-effects to which the usual semi-classical treatment is blind. They violate the de Sitter symmetry and lead to a finite quantum break-time of the de Sitter state equal to the de Sitter radius times N. We also point out that the quantum-break time is inversely proportional to the number of particle species in the theory. Thus, the quantum break-time imposes the following consistency condition: older and species-richer universes must have smaller cosmological constants. For the maximal, phenomenologically acceptable number of species, the observed cosmological constant would saturate this bound if our Universe were 10100 years old in its entire classical history.

Accelerometer-assessed sedentary work, leisure time and cardio-metabolic biomarkers during one year: Effectiveness of a cluster randomized controlled trial in parents with a sedentary occupation and young children.

PubMed

Pesola, Arto J; Laukkanen, Arto; Heikkinen, Risto; Sipilä, Sarianna; Sääkslahti, Arja; Finni, Taija

2017-01-01

It is unknown whether reducing sedentary time at work and during leisure time is possible and effective during one year. Office workers with young children were recruited for this one-year cluster-randomized controlled trial through kindergartens and primary schools from 7 clusters in the city of Jyväskylä, Finland. After a lecture, face-to-face tailored counseling was used to set contractually binding goals regarding reducing and breaking up sitting periods and increasing light intensity physical activity during work and leisure time. Primary outcomes of total, work and leisure sedentary time (<100 counts/min, cpm), light activity time (<2020 cpm), moderate-to-vigorous activity time (MVPA) and breaks/sedentary hour were assessed with a waist-worn Alive -accelerometer for 7 days, 5 times during the year. Anthropometrics (DXA), fasting biomarkers and self-reported diet were assessed as secondary outcomes. Data were collected between 2011-2013 and analyzed between 2013-2016 with a linear mixed-effects model fit by REML using likelihood ratio test and intention-to-treat-principle. Participants from intervention (N = 71) and control (N = 62) regions were assessed at baseline and 117 completed the study. Sedentary leisure time decreased [-21.2 (95% CI -37.3 to -5.1) min/8 hours, likelihood ratio P<0.001] and light activity time [13.4 (-2.2 to 29.0) min/8 hours, P = 0.008] and breaks per sedentary hour [1.0 (-0.2 to 2.2), P = 0.010] increased in the intervention group as compared to controls at 3 months. The decrease in sedentary leisure time was maintained throughout the year [-7.9 (-24.0 to 8.3) min/8 hours, P = 0.029]. Small decreases in the control group's work and leisure MVPA were observed mostly at 3 months. Small favorable intervention effects were observed for fasting plasma glucose at 3 months and for leg lean mass and apoB/apoA-1 ratio at 12 months, with no changes in other outcomes. Behavioral counseling induced a small decline in sedentary leisure time throughout one year in parents with a sedentary occupation and young children. Small concurrent changes in different biomarkers suggest that reducing sedentary leisure time during one year may be beneficial. ISRCTN28668090, registered 30 November 2011.

Induction of chromatin damage and distribution of isochromatid breaks in human fibroblast cells exposed to heavy ions

NASA Technical Reports Server (NTRS)

Kawata, Tetsuya; Ito, Hisao; Motoori, Ken; Ueda, Takuya; Shigematsu, Naoyuki; Furusawa, Yoshiya; Durante, Marco; George, Kerry; Wu, Honglu; Cucinotta, Francis A.

2002-01-01

The frequency of chromatid breaks and the distribution of isochromatid breaks were measured in G2-phase normal human fibroblasts prematurely condensed a short time after exposure to low- or high-LET radiations. The average number of isochromatid breaks from a single particle traversal increased with increasing LET values, while the average number of chromatid-type breaks appeared to reach a plateau. The distribution of isochromatid breaks after high-LET iron particles exposure was overdispersed compared to gamma-rays, indicating that a single iron particle traversal through a cell nucleus can produce multiple isochromatid breaks.

Induction of chromatin damage and distribution of isochromatid breaks in human fibroblast cells exposed to heavy ions.

PubMed

Kawata, Tetsuya; Ito, Hisao; Motoori, Ken; Ueda, Takuya; Shigematsu, Naoyuki; Furusawa, Yoshiya; Durante, Marco; George, Kerry; Wu, Honglu; Cucinotta, Francis A

2002-12-01

The frequency of chromatid breaks and the distribution of isochromatid breaks were measured in G2-phase normal human fibroblasts prematurely condensed a short time after exposure to low- or high-LET radiations. The average number of isochromatid breaks from a single particle traversal increased with increasing LET values, while the average number of chromatid-type breaks appeared to reach a plateau. The distribution of isochromatid breaks after high-LET iron particles exposure was overdispersed compared to gamma-rays, indicating that a single iron particle traversal through a cell nucleus can produce multiple isochromatid breaks.

Do children report differently from their parents and from observed data? Cross-sectional data on fruit, water, sugar-sweetened beverages and break-time foods.

PubMed

van de Gaar, V M; Jansen, W; van der Kleij, M J J; Raat, H

2016-04-18

Reliable assessment of children's dietary behaviour is needed for research purposes. The aim of this study was (1) to investigate the level of agreement between observed and child-reported break-time food items; and (2) to investigate the level of agreement between children's reports and those of their parents regarding children's overall consumption of fruit, water and sugar-sweetened beverages (SSB). The children in this study were 9-13 years old, attending primary schools in Rotterdam, the Netherlands. Children were observed with respect to foods brought for break-time at school. At the same day, children completed a questionnaire in which they were asked to recall the food(s) they brought to school to consume during break-time. Only paired data (observed and child-reported) were included in the analyses (n = 407 pairs). To determine each child's daily consumption and average amounts of fruit, water and SSB consumed, children and their parents completed parallel questionnaires. Only paired data (parent-reported and child-reported) were included in the analyses (n = 275 pairs). The main statistical measures were level of agreement between break-time foods, fruit, water and SSB; and Intra-class Correlation Coefficients (ICC). More children reported bringing sandwiches and snacks for break-time than was observed (73 % vs 51 % observed and 84 % vs 33 % observed). The overall agreement between observed and child-reported break-time foods was poor to fair, with ICC range 0.16-0.39 (p < 0.05). Children reported higher average amounts of SSB consumed than did their parents (1.3 vs 0.9 L SSB, p < 0.001). Child and parent estimations of the child's water and fruit consumption were similar. ICC between parent and child reports was poor to good (range 0.22-0.62, p < 0.05). Children report higher on amount of break-time foods as compared to observations and children's reports of SSB consumption are higher than those of their parents. Since the level of agreement between the observed break-time foods and that reported by children and the agreement of child's intake between parent and child reports are relatively weak, future studies should focus on improving methods of evaluating children's consumption behaviour or on ways on how to best use and interpret multiple-source dietary intake data. Current Controlled Trials NTR3400 .

Using machine learning to identify structural breaks in single-group interrupted time series designs.

PubMed

Linden, Ariel; Yarnold, Paul R

2016-12-01

Single-group interrupted time series analysis (ITSA) is a popular evaluation methodology in which a single unit of observation is being studied, the outcome variable is serially ordered as a time series and the intervention is expected to 'interrupt' the level and/or trend of the time series, subsequent to its introduction. Given that the internal validity of the design rests on the premise that the interruption in the time series is associated with the introduction of the treatment, treatment effects may seem less plausible if a parallel trend already exists in the time series prior to the actual intervention. Thus, sensitivity analyses should focus on detecting structural breaks in the time series before the intervention. In this paper, we introduce a machine-learning algorithm called optimal discriminant analysis (ODA) as an approach to determine if structural breaks can be identified in years prior to the initiation of the intervention, using data from California's 1988 voter-initiated Proposition 99 to reduce smoking rates. The ODA analysis indicates that numerous structural breaks occurred prior to the actual initiation of Proposition 99 in 1989, including perfect structural breaks in 1983 and 1985, thereby casting doubt on the validity of treatment effects estimated for the actual intervention when using a single-group ITSA design. Given the widespread use of ITSA for evaluating observational data and the increasing use of machine-learning techniques in traditional research, we recommend that structural break sensitivity analysis is routinely incorporated in all research using the single-group ITSA design. © 2016 John Wiley & Sons, Ltd.

Dynamic decision making for dam-break emergency management - Part 1: Theoretical framework

NASA Astrophysics Data System (ADS)

Peng, M.; Zhang, L. M.

2013-02-01

An evacuation decision for dam breaks is a very serious issue. A late decision may lead to loss of lives and properties, but a very early evacuation will incur unnecessary expenses. This paper presents a risk-based framework of dynamic decision making for dam-break emergency management (DYDEM). The dam-break emergency management in both time scale and space scale is introduced first to define the dynamic decision problem. The probability of dam failure is taken as a stochastic process and estimated using a time-series analysis method. The flood consequences are taken as functions of warning time and evaluated with a human risk analysis model (HURAM) based on Bayesian networks. A decision criterion is suggested to decide whether to evacuate the population at risk (PAR) or to delay the decision. The optimum time for evacuating the PAR is obtained by minimizing the expected total loss, which integrates the time-related probabilities and flood consequences. When a delayed decision is chosen, the decision making can be updated with available new information. A specific dam-break case study is presented in a companion paper to illustrate the application of this framework to complex dam-breaching problems.

High-LET radiation-induced aberrations in prematurely condensed G2 chromosomes of human fibroblasts

NASA Technical Reports Server (NTRS)

Kawata, T.; Gotoh, E.; Durante, M.; Wu, H.; George, K.; Furusawa, Y.; Cucinotta, F. A.; Dicello, J. F. (Principal Investigator)

2000-01-01

PURPOSE: To determine the number of initial chromatid breaks induced by low- or high-LET irradiations, and to compare the kinetics of chromatid break rejoining for radiations of different quality. MATERIAL AND METHODS: Exponentially growing human fibroblast cells AG1522 were irradiated with gamma-rays, energetic carbon (290MeV/u), silicon (490MeV/u) and iron (200 and 600 MeV/u). Chromosomes were prematurely condensed using calyculin A. Chromatid breaks and exchanges in G2 cells were scored. PCC were collected after several post-irradiation incubation times, ranging from 5 to 600 min. RESULTS: The kinetics of chromatid break rejoining following low- or high-LET irradiation consisted of two exponential components representing a rapid and a slow time constant. Chromatid breaks decreased rapidly during the first 10min after exposure, then continued to decrease at a slower rate. The rejoining kinetics were similar for exposure to each type of radiation. Chromatid exchanges were also formed quickly. Compared to low-LET radiation, isochromatid breaks were produced more frequently and the proportion of unrejoined breaks was higher for high-LET radiation. CONCLUSIONS: Compared with gamma-rays, isochromatid breaks were observed more frequently in high-LET irradiated samples, suggesting that an increase in isochromatid breaks is a signature of high-LET radiation exposure.

Hydrodynamic response of a fringing coral reef to a rise in mean sea level

NASA Astrophysics Data System (ADS)

Taebi, Soheila; Pattiaratchi, Charitha

2014-07-01

Ningaloo Reef, located along the northwest coast of Australia, is one of the longest fringing coral reefs in the world extending ~300 km. Similar to other fringing reefs, it consists of a barrier reef ~1-6 km offshore with occasional gaps, backed by a shallow lagoon. Wave breaking on the reef generates radiation stress gradients that produces wave setup across the reef and lagoon and mean currents across the reef. A section of Ningaloo Reef at Sandy Bay was chosen as the focus of an intense 6-week field experiment and numerical simulation using the wave model SWAN coupled to the three-dimensional circulation model ROMS. The physics of nearshore processes such as wave breaking, wave setup and mean flow across the reef was investigated in detail by examining the various momentum balances established in the system. The magnitude of the terms and the distance of their peaks from reef edge in the momentum balance were sensitive to the changes in mean sea level, e.g. the wave forces decreased as the mean water depth increased (and hence, wave breaking dissipation was reduced). This led to an increase in the wave power at the shoreline, a slight shift of the surf zone to the lee side of the reef and changes in the intensity of the circulation. The predicted hydrodynamic fields were input into a Lagrangian particle tracking model to estimate the transport time scale of the reef-lagoon system. Flushing time of the lagoon with the open ocean was computed using two definitions in renewal of semi-enclosed water basins and revealed the sensitivity of such a transport time scale to methods. An increase in the lagoon exchange rate at smaller mean sea-level rise and the decrease at higher mean sea-level rise was predicted through flushing time computed using both methods.

GPUs in a computational physics course

NASA Astrophysics Data System (ADS)

Adler, Joan; Nissim, Gal; Kiswani, Ahmad

2017-10-01

In an introductory computational physics class of the type that many of us give, time constraints lead to hard choices on topics. Everyone likes to include their own research in such a class but an overview of many areas is paramount. Parallel programming algorithms using MPI is one important topic. Both the principle and the need to break the “fear barrier” of using a large machine with a queuing system via ssh must be sucessfully passed on. Due to the plateau in chip development and to power considerations future HPC hardware choices will include heavy use of GPUs. Thus the need to introduce these at the level of an introductory course has arisen. Just as for parallel coding, explanation of the benefits and simple examples to guide the hesitant first time user should be selected. Several student projects using GPUs that include how-to pages were proposed at the Technion. Two of the more successful ones were lattice Boltzmann and a finite element code, and we present these in detail.

A study of degradation of plates for nickel-cadmium spacecraft cells

NASA Technical Reports Server (NTRS)

Scott, W. R.

1974-01-01

The relative merits of coining and not coining of sintered nickel oxide and cadmium plates was investigated. Sample plate materials from most commercial cell suppliers were obtained and characterized for properties that may correlate with the tendency toward physical disintegration during handling and over long periods of time in the cell. Special test methods were developed to obtain comparative data in a short time. A wide range of physical properties and coining thickness was observed, resulting in a range of responses. The stronger materials resisted loss of sinter better than weaker materials whether or not coined. Coining improved handling and resistance to electrochemical cycling of weaker materials. The mechanism of break-down of positive plate edges under cycling appears to be the same as that of thickening and blistering. Brittle, nonadherent sinter, resulting from certain impregnation processes, is the most vulnerable to degradation. It is concluded that the latter type of materials should be coined, but coining of strong materials is optional.

78 FR 76757 - Regulatory Guidance on Hours of Service of Drivers Rest Break Requirement; Drivers Who Become...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-19

... days as ``short haul'' drivers exempt from the break rule, but who occasionally exceed the short haul distance or time limits. Such drivers are then subject to the break requirement and must prepare a record-of-duty-status (RODS) for the day. The intent of the break rule would be satisfied if drivers in...

46 CFR 196.30-20 - Breaking of safety valve seal.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 7 2011-10-01 2011-10-01 false Breaking of safety valve seal. 196.30-20 Section 196.30... OPERATIONS Reports of Accidents, Repairs, and Unsafe Equipment § 196.30-20 Breaking of safety valve seal. (a) If at any time it is necessary to break the seal on a safety valve for any purpose, the Chief...

46 CFR 196.30-20 - Breaking of safety valve seal.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Breaking of safety valve seal. 196.30-20 Section 196.30... OPERATIONS Reports of Accidents, Repairs, and Unsafe Equipment § 196.30-20 Breaking of safety valve seal. (a) If at any time it is necessary to break the seal on a safety valve for any purpose, the Chief...

Physical Properties Of Acupuncture Needles: Do Disposable Acupuncture Needles Break With Normal Use

DTIC Science & Technology

2016-06-01

Lamb shank, which has complexity of tendon, fascia, and bone, was used to mimic human tissue. The needles (n=10) were stressed in the tissue substitute...needles were re-imaged after stressing and visually assessed. RESULTS: Only one manufacturing scuff mark was noted out of 90 needles before stress ...testing. Needles buckled but did not break when they were stressed beyond normal clinical use. No cracks or fractures were noted after stress

The Chemical Adventures of Sherlock Holmes: The Baker Street Burning

NASA Astrophysics Data System (ADS)

Waddell, Thomas G.; Rybolt, Thomas R.

1998-04-01

This story describes a chemical mystery with an emphasis on forensic chemistry, physical properties, and qualitative organic analysis. This is the ninth article in a series presenting a scientific problem in mystery form in the context of the popular and beloved characters Sherlock Holmes and Dr. Watson. There is a break in the story where the reader (students and teachers) can ponder and solve the mystery. Sherlock Holmes provides his solution in the paragraphs following this break.

The Chemical Adventures of Sherlock Holmes: The Case of Three

NASA Astrophysics Data System (ADS)

Rybolt, Thomas R.; Waddell, Thomas G.

2002-04-01

This story is a chemical mystery with an emphasis on simple physical properties and chemical characterization of metals. It is the 13th in a series presenting scientific problems in mystery format in the context of the popular and beloved characters Sherlock Holmes and Dr. Watson. There is a break in the story where the reader (students and teachers) can ponder and solve the mystery. Sherlock Holmes provides his solution in the paragraphs following this break.

Dynamics of symmetry breaking during quantum real-time evolution in a minimal model system.

PubMed

Heyl, Markus; Vojta, Matthias

2014-10-31

One necessary criterion for the thermalization of a nonequilibrium quantum many-particle system is ergodicity. It is, however, not sufficient in cases where the asymptotic long-time state lies in a symmetry-broken phase but the initial state of nonequilibrium time evolution is fully symmetric with respect to this symmetry. In equilibrium, one particular symmetry-broken state is chosen as a result of an infinitesimal symmetry-breaking perturbation. From a dynamical point of view the question is: Can such an infinitesimal perturbation be sufficient for the system to establish a nonvanishing order during quantum real-time evolution? We study this question analytically for a minimal model system that can be associated with symmetry breaking, the ferromagnetic Kondo model. We show that after a quantum quench from a completely symmetric state the system is able to break its symmetry dynamically and discuss how these features can be observed experimentally.

-> Air entrainment and bubble statistics in three-dimensional breaking waves

NASA Astrophysics Data System (ADS)

Deike, L.; Popinet, S.; Melville, W. K.

2016-02-01

Wave breaking in the ocean is of fundamental importance for quantifying wave dissipation and air-sea interaction, including gas and momentum exchange, and for improving air-sea flux parametrizations for weather and climate models. Here we investigate air entrainment and bubble statistics in three-dimensional breaking waves through direct numerical simulations of the two-phase air-water flow using the Open Source solver Gerris. As in previous 2D simulations, the dissipation due to breaking is found to be in good agreement with previous experimental observations and inertial-scaling arguments. For radii larger than the Hinze scale, the bubble size distribution is found to follow a power law of the radius, r-10/3 and to scale linearly with the time dependent turbulent dissipation rate during the active breaking stage. The time-averaged bubble size distribution is found to follow the same power law of the radius and to scale linearly with the wave dissipation rate per unit length of breaking crest. We propose a phenomenological turbulent bubble break-up model that describes the numerical results and existing experimental results.

Epidemiology of urban water distribution systems

NASA Astrophysics Data System (ADS)

Bardet, Jean-Pierre; Little, Richard

2014-08-01

Urban water distribution systems worldwide contain numerous old and fragile pipes that inevitably break, flood streets and damage property, and disrupt economic and social activities. Such breaks often present dramatically in temporal clusters as occurred in Los Angeles during 2009. These clustered pipe breaks share many characteristics with human mortality observed during extreme climatological events such as heat waves or air pollution. Drawing from research and empirical studies in human epidemiology, a framework is introduced to analyze the time variations of disruptive pipe breaks that can help water agencies better understand clustered pipe failures and institute measures to minimize the disruptions caused by them. It is posited that at any time, a cohort of the pipes comprising the water distribution system will be in a weakened state due to fatigue and corrosion. This frail cohort becomes vulnerable during normal operations and ultimately breaks due to rapid increase in crack lengths induced by abnormal stressors. The epidemiological harvesting model developed in this paper simulates an observed time series of monthly pipe breaks and has both explanatory and predictive power. It also demonstrates that models from nonengineering disciplines such as medicine can provide improved insights into the performance of infrastructure systems.

The timing of bud break in warming conditions: variation among seven sympatric conifer species from Eastern Canada

NASA Astrophysics Data System (ADS)

Rossi, Sergio; Isabel, Nathalie

2017-11-01

Phenological changes are expected with the ongoing global warming, which could create mismatches in the growth patterns among sympatric species or create synchrony with insect herbivores. In this study, we performed a comparative assessment of the timings of bud break among seven conifer species of Eastern Canada by evaluating seedling development in growth chambers under different temperatures (16, 20 and 24 °C). Bud break occurred earliest in Larix laricina, while Pinus strobus and Pinus resinosa had the latest. Warmer conditions advanced bud break, with the greatest effects being observed at the lower temperatures. Mixed models estimated that one additional degree of temperature produced advancements of 5.3 and 2.1 days at 16 and 20 °C, respectively. The hypothesis of an asynchronous change between species under warming was demonstrated only for the last phenological phases (split buds and exposed shoots), and principally in pines. Abies balsamea showed changes in bud break comparable with the other species analysed, rejecting the hypothesis of mismatches under warmer conditions. The observed non-linear responses of the timings of bud break to warming suggest that the major changes in bud phenology should be expected at the lowest temperatures.

The Playground as Classroom

ERIC Educational Resources Information Center

Santa, Anne

2007-01-01

Recess gives children the freedom and the time to explore the natural world, socialize, and exercise. But in many school systems, recess time is shrinking to make time for test preparation. In support of recess, Anne Santa cites research showing that recess breaks can actually improve learning because student attentiveness improves after a break.…

Social and Physical Aggression Trajectories from Childhood through Late Adolescence: Predictors of Psychosocial Maladjustment at Age 18

ERIC Educational Resources Information Center

Ehrenreich, Samuel E.; Beron, Kurt J.; Underwood, Marion K.

2016-01-01

This research examined whether following social and physical aggression trajectories across Grades 3-12 predicted psychological maladjustment. Teachers rated participants' (n = 287, 138 boys) aggressive behavior at the end of each school year. Following the 12th grade, psychosocial outcomes were measured: rule-breaking behaviors, internalizing…

Breaking from Traditionalism: Strategies for the Recruitment of Physical Education Teachers

ERIC Educational Resources Information Center

O'Neil, Kason; Richards, K. Andrew R.

2018-01-01

Teacher education programs across the country are being asked to systematically and deliberately recruit teacher candidates who are not only highly qualified, but represent diverse backgrounds. Coupled with dwindling enrollments, these programs may want to reevaluate the types of students recruited into a career in physical education. This article…

Using Dance Dance Revolution in Physical Education

ERIC Educational Resources Information Center

Trout, Josh; Zamora, Karra

2005-01-01

Sedentary lifestyles are often to blame for overweight and obesity, which is the second leading cause of preventable deaths in the U.S. (USDHHS, 2001). While video games have historically been identified as the culprit of inactivity, new interactive video games make participants break a sweat. Some physical educators have begun integrating this…

Strategies for Supporting Recess in Elementary Schools

ERIC Educational Resources Information Center

Centers for Disease Control and Prevention, 2014

2014-01-01

Recess provides students with a needed break from their structured school day. It can improve children's physical, social, and emotional well-being, and enhance learning. Recess helps children meet the goal of 60 minutes of physical activity (PA) each day, as recommended by the US Department of Health and Human Services. National…

Fermilab Today

Science.gov Websites

Fundamental Physics in the Non-Linear Regime 3:30 p.m. Director's Coffee Break - 2nd Flr X-Over 4:00 p.m. All Week archive Fermilab Safety Tip of the Week archive Linear Collider News archive Fermilab Today Committee ECFA Study of Physics and Detectors for a Linear Collider" and GDE member, explained the

Expected Values for Pedometer-Determined Physical Activity in Youth

ERIC Educational Resources Information Center

Tudor-Locke, Catrine; McClain, James J.; Hart, Teresa L.; Sisson, Susan B.; Washington, Tracy L.

2009-01-01

This review assembles pedometry literature focused on youth, with particular attention to expected values for habitual, school day, physical education class, recess, lunch break, out-of-school, weekend, and vacation activity. From 31 studies published since 1999, we constructed a youth habitual activity step-curve that indicates: (a) from ages 6…

A Two-Step Integrated Theory of Everything (TOE)

NASA Astrophysics Data System (ADS)

Colella, Antonio

2017-01-01

Two opposing TOE visions are my Two-Step (physics/math) and Hawking's single math step. My Two-Step should replace the single step because of the latter's near zero results after a century of attempts. My physics step had 3 goals. First ``Everything'' was defined as 20 interrelated amplified theories (e.g. string, Higgs forces, spontaneous symmetry breaking, particle decays, dark matter, dark energy, stellar black holes) and their intimate physical interrelationships. Amplifications of Higgs forces theory (e.g. matter particles and their associated Higgs forces were one and inseparable, spontaneous symmetry breaking was bidirectional and caused by high temperatures not Higgs forces, and sum of 8 Higgs forces of 8 permanent matter particles was dark energy) were key to my Two-Step TOE. The second goal answered all outstanding physics questions: what were Higgs forces, dark energy, dark matter, stellar black holes, our universe's creation, etc.? The third goal provided correct inputs for the two part second math step, an E8 Lie algebra for particles and an N-body cosmology simulation (work in progress). Scientific advancement occurs only if the two opposing TOEs are openly discussed/debated.

Monitoring the drastic growth of ship breaking yards in Sitakunda: a threat to the coastal environment of Bangladesh.

PubMed

Abdullah, Hasan Muhammad; Mahboob, M Golam; Banu, Mehmuna R; Seker, Dursun Zafer

2013-05-01

The vast coastal and marine resources that occur along the southern edge of Bangladesh make it one of the most productive areas of the world. However, due to growing anthropogenic impacts, this area is under considerable environmental pressure from both physical and chemical stress factors. Ship breaking, or the dismantling and demolition of out-of-service ocean-going vessels, has become increasingly common in many coastal areas. To investigate the extent of ship breaking activities in Bangladesh along the Sitakunda coast, various spatial and non-spatial data were obtained, including remote sensing imagery, statistical records and published reports. Impacts to coastal and marine life were documented. Available data show that ship breaking activities cause significant physical disturbance and release toxic materials into the environment, resulting in adverse effects to numerous marine taxonomic groups such as fish, mammals, birds, reptiles, plants, phytoplankton, zooplankton and benthic invertebrates. Landsat imagery illustrates that the negatively impacted coastal area has grown 308.7 % from 367 ha in 1989 to 1,133 ha in 2010. Physicochemical and biological properties of coastal soil and water indicate substantially elevated pollution that poses a risk of local, regional and even global contamination through sea water and atmospheric transport. While damage to the coastal environment of Bangladesh is a recognized hazard that must be addressed, the economic benefits of ship breaking through job creation and fulfilling the domestic demand for recycled steel must be considered. Rather than an outright ban on beach breaking of ships, the enterprise must be recognized as a true and influential industry that should be held responsible for developing an economically viable and environmentally proactive growth strategy. Evolution of the industry toward a sustainable system can be aided through reasonable and enforceable legislative and judicial action that takes a balanced approach, but does not diminish the value of coastal conservation.

Physical and mechanical properties of LDPE incorporated with different starch sources

NASA Astrophysics Data System (ADS)

Kormin, Shaharuddin; Kormin, Faridah; Dalour Hossen Beg, Mohammad; Bijarimi Mat Piah, Mohd

2017-08-01

In this study it was investigated the incorporation of different starches, such as sago starch, corn starch, potato starch, tapioca starch and wheat starch, in low-density polyethylene matrix (LDPE) to enhanced mechanical properties and to obtain partially biodegradable product with the aim to reduce the plastics wastes in the environment. For comparison, virgin LDPE, LDPE with different sources of starch blends were prepared and characterized under the same conditions. The starches were mixed to the LDPE using a twin screw extruder to guarantee the homogeneity of the formulations. The compound were shaping processed by injection moulding. The characterization of those compounds was done by physical (density, MFI), mechanical (Universal tensile machine). The addition of starch to LDPE reduced the MFI values, the tensile strength, elongation at break and impact strength, whereas the elastic modulus, flexural modulus and flexural strength increased. LDPE/SS show the good mechanical behavior compared to other formulation. The physical and mechanical properties were evident when 5 and 30 wt% were added. Water uptake increased with increased starch content and immersion time. The time taken for the composites to equilibrate was about one month even when they were immersed completely in water.

Collisional PIC Simulations of Particles in Magnetic Fields

NASA Astrophysics Data System (ADS)

Peter, William

2003-10-01

Because of the long range of Coloumb forces, collisions with distant particles in plasmas are more important than collisions with near neighbors. In addition, many problems in space physics and magnetic confinement include regions of weak magnetic field where the MHD approximation breaks down. A particle-in-cell code based on the quiet direct simulation Monte-Carlo method(B. J. Albright, W. Daughton, D. Lemons, D. Winske, and M. E. Jones, Physics of Plasmas) 9, 1898 (2002). is being developed to study collisional (e.g., ν ˜ Ω) particle motion in magnetic fields. Primary application is to energetic particle loss in the radiation belts(K. Papadopoulos, COSPAR Meeting, Houston, TX, Oct., 2002.) at a given energy and L-shell. Other applications include trapping in rotating field-reversed configurations(N. Rostoker and A. Qerushi, Physics of Plasmas) 9, 3057 (2002)., and electron behavior in magnetic traps(V. Gorgadze, T. Pasquini, J. S. Wurtele, and J. Fajans, Bull. Am. Phys. Soc.) 47, 127 (2002).. The use of the random time-step method(W. Peter, Bull. Am. Phys. Soc.) 47, 52 (2002). to decrease simulation times by 1-2 orders of magnitude is also being studied.

[A PARADIGM SHIFT IN THE PERCEPTION OF HEALTH MAINTENANCE FROM INCREASING PHYSICAL ACTIVITY TO DECREASING PHYSICAL INACTIVITY].

PubMed

Rotman, Dani; Constantini, Naama

2016-06-01

Modern man spends most of his waking hours (50-70%) in one form or another of sedentary behavior, defined as activity conducted in a sitting or reclining position involving low energy expenditure. The remaining waking hours are spent performing low intensity physical activity (25-45%) and medium-high intensity physical activity (less than 5%): Despite this distribution, medical research has focused on the impact of increasing medium-high intensity physical activity and many health organizations' recommendations are in accordance. In recent years, research conducted has begun to examine the effect inactivity has on health and has shown that excess sedentary behaviour is an independent risk factor for a wide range of medical problems such as obesity, metabolic syndrome, poor cardiovascular health profile, diabetes mellitus, and possibly cancer. Although the higher risk brought on by sedentary behaviour is partially reduced by increasing medium-high intensity physical activity, it is not completely neutralized. One way to diminish the harm caused by long hours of sitting is to take short breaks during periods of prolonged sitting in order to walk. According to these findings, it is worthwhile to recommend reducing the hours spent in sedentary behaviour, or at least to take frequent short breaks ("activity snacks") during periods of prolonged sitting to get up and walk around.

Controlled breaks as a fatigue countermeasure on the flight deck

NASA Technical Reports Server (NTRS)

Neri, David F.; Oyung, Raymond L.; Colletti, Laura M.; Mallis, Melissa M.; Tam, Patricia Y.; Dinges, David F.

2002-01-01

BACKGROUND: A major challenge for flight crews is the need to maintain vigilance during long, highly automated nighttime flights. No system currently exists to assist in managing alertness, and countermeasure options are limited. Surveys reveal many pilots use breaks as an in-flight countermeasure, but there have been no controlled studies of their effectiveness. HYPOTHESIS: We hypothesized that brief, regular breaks could improve alertness and performance during an overnight flight. METHOD: A 6-h, uneventful, nighttime flight in a Boeing 747-400 flight simulator was flown by fourteen two-man crews. The 14 subjects in the treatment group received 5 short breaks spaced hourly during cruise; the 14 subjects in the control group received 1 break in the middle of cruise. Continuous EEG/EOG, subjective sleepiness, and psychomotor vigilance performance data were collected. RESULTS: During the latter part of the night, the treatment group showed significant reductions for 15 min post-break in slow eye movements, theta-band activity, and unintended sleep episodes compared with the control group. The treatment group reported significantly greater subjective alertness for up to 25 min post-break, with strongest effects near the time of the circadian trough. There was no evidence of objective vigilance performance improvement at 15-25 min post-break, with expected performance deterioration occurring due to elevated sleep drive and circadian time. CONCLUSIONS: The physiological and subjective data indicate the breaks reduced nighttime sleepiness for at least 15 min post-break and may have masked sleepiness for up to 25 min, suggesting the potential usefulness of short-duration breaks as an in-flight fatigue countermeasure.

Controlled breaks as a fatigue countermeasure on the flight deck.

PubMed

Neri, David F; Oyung, Raymond L; Colletti, Laura M; Mallis, Melissa M; Tam, Patricia Y; Dinges, David F

2002-07-01

A major challenge for flight crews is the need to maintain vigilance during long, highly automated nighttime flights. No system currently exists to assist in managing alertness, and countermeasure options are limited. Surveys reveal many pilots use breaks as an in-flight countermeasure, but there have been no controlled studies of their effectiveness. We hypothesized that brief, regular breaks could improve alertness and performance during an overnight flight. A 6-h, uneventful, nighttime flight in a Boeing 747-400 flight simulator was flown by fourteen two-man crews. The 14 subjects in the treatment group received 5 short breaks spaced hourly during cruise; the 14 subjects in the control group received 1 break in the middle of cruise. Continuous EEG/EOG, subjective sleepiness, and psychomotor vigilance performance data were collected. During the latter part of the night, the treatment group showed significant reductions for 15 min post-break in slow eye movements, theta-band activity, and unintended sleep episodes compared with the control group. The treatment group reported significantly greater subjective alertness for up to 25 min post-break, with strongest effects near the time of the circadian trough. There was no evidence of objective vigilance performance improvement at 15-25 min post-break, with expected performance deterioration occurring due to elevated sleep drive and circadian time. The physiological and subjective data indicate the breaks reduced nighttime sleepiness for at least 15 min post-break and may have masked sleepiness for up to 25 min, suggesting the potential usefulness of short-duration breaks as an in-flight fatigue countermeasure.

Risk factors for retinal breaks in patients with symptom of floaters.

PubMed

Singalavanija, Apichart; Amornrattanapan, Chutiwan; Nitiruangjarus, Kanjanee; Tongsai, Sasima

2010-06-01

To identify the risk factors of retinal breaks in patients with the symptom of floaters, and to determine the association between those risk factors and retinal breaks. A retrospective analytic study of 184 patients (55 males and 129 females) that included 220 eyes was conducted. Patient information such as age, symptoms (multiple floaters, flashing), duration of symptom, refractive error, history of cataract surgery, family history of retinal detachment, and complete eye examination were recorded. The patients were divided into two groups, the first group (control group) had symptoms of floaters and no retinal breaks, the second group (retinal breaks group) had symptoms of floaters with retinal breaks. Chi-square test, and the multiple logistic regression were used for statistical analysis. Two hundred twenty eyes, 175 eyes of the control group and 45 eyes of the retinal breaks group were examined and included in this study. The multiple logistic regression analysis revealed that patients with multiple floaters, and floaters and flashing increased the risk of retinal breaks to 5.8 and 4.3 times, respectively, when compared to patients with single floater or floaters alone. Lattice degeneration increased the risk of retinal breaks to 5.9 times when compared to eyes that did not have lattice degeneration. Multiple floaters, flashing and lattice degeneration are risk factors of retinal breaks in patients with symptoms of floaters. Therefore, it is important for the ophthalmologists to be aware of these risk factors and the patients at risk should have follow-up examinations.

Discrete symmetry breaking and baryon currents in U(N) and SU(N) gauge theories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lucini, B.; Patella, A.

2009-06-15

In SU(N) gauge theories with fermions in the fundamental or in a two-index (either symmetric or antisymmetric) representation formulated on a manifold with at least one compact dimension with nontrivial holonomy the discrete symmetries C, P, and T are broken at small enough size of the compact direction(s) for certain values of N. We show that for those N in the broken phase a nonzero baryon current wrapping in the compact direction exists, which provides a measurable observable for the breaking of C, P, and T. We prove that in all cases where the current is absent there is nomore » breaking of those discrete symmetries. This includes the limit N{yields}{infinity} of the SU(N) gauge theory with symmetric or antisymmetric fermions and U(N) gauge theory at any value of N. We then argue that the component of the baryon current in the compact direction is the physical order parameter for C, P, and T breaking due to the breaking of Lorentz invariance.« less

Minimally doubled fermions and spontaneous chiral symmetry breaking

NASA Astrophysics Data System (ADS)

Osmanaj (Zeqirllari), Rudina; Hyka (Xhako), Dafina

2018-03-01

Chiral symmetry breaking in massless QCD is a very important feature in the current understanding of low energy physics. Low - lying Dirac modes are suitable to help us understand the spontaneous chiral symmetry breaking, since the formation of a non zero chiral condensate is an effect of their accumulation near zero. The Banks - Casher relation links the spectral density of the Dirac operator to the condensate with an identity that can be read in both directions. In this work we propose a spectral method to achieve a reliable determination of the density of eigenvalues of Dirac operator near zero using the Gauss - Lanczos quadrature. In order to understand better the dynamical chiral symmetry breaking and use the method we propose, we have chosen to work with minimally doubled fermions. These kind of fermions have been proposed as a strictly local discretization of the QCD fermions action, which preserves chiral symmetry at finite cut-off. Being chiral fermions, is easier to work with them and their low - lying Dirac modes and to understand the dynamical spontaneous chiral symmetry breaking.

Sedentary Patterns, Physical Activity, and Cardiorespiratory Fitness in Association to Glycemic Control in Type 2 Diabetes Patients

PubMed Central

Sardinha, Luís B.; Magalhães, João P.; Santos, Diana A.; Júdice, Pedro B.

2017-01-01

Background: Sedentary behavior has been considered an independent risk factor for type-2 diabetes (T2D), with a negative impact on several physiological outcomes, whereas breaks in sedentary time (BST) have been proposed as a viable solution to mitigate some of these effects. However, little is known about the independent associations of sedentary pursuits, physical activity, and cardiorespiratory fitness (CRF) variables with glycemic control. We investigated the independent associations of total sedentary time, BST, moderate-to-vigorous physical activity (MVPA), and CRF with glycemic outcomes in patients with T2D. Methods: Total sedentary time, BST, and MVPA were assessed in 66 participants (29 women) with T2D, using accelerometry. Glucose and insulin were measured during a mixed meal tolerance test, with the respective calculations of HOMA-IR and Matsuda index. Glycated hemoglobin (HbA1c) was also analyzed. CRF was measured in a maximal treadmill test with breath-by-breath gases analysis. Multiple regressions were used for data analysis. Results: Regardless of CRF, total sedentary time was positively associated with HbA1c (β = 0.25, p = 0.044). Adjusting for MVPA, total sedentary time was related to fasting glucose (β = 0.32, p = 0.037). No associations between total sedentary time and the remaining glycemic outcomes, after adjusting for MVPA. BST had favorable associations with HOMA-IR (β = −0.28, p = 0.047) and fasting glucose (β = −0.25, p = 0.046), when adjusted for MVPA, and with HOMA-IR (β = −0.25, p = 0.036), Matsuda index (β = 0.26, p = 0.036), and fasting glucose (β = −0.22, p = 0.038), following adjustment for CRF. When adjusting for total sedentary time, only CRF yielded favorable associations with HOMA-IR (β = −0.29, p = 0.039), fasting glucose (β = −0.32, p = 0.012), and glucose at 120-min (β = −0.26, p = 0.035), and no associations were found for MVPA with none of the metabolic outcomes. Conclusion: The results from this study suggest that sedentary time and patterns are relevant for the glycemic control in patients with T2D. Still, MVPA and CRF counteracted most of the associations for total sedentary time but not for the BST. MVPA was not associated with metabolic outcomes, and CRF lost some of the associations with glycemic indicators when adjusted for total sedentary time. Future interventions aiming to control/improve T2D must consider reducing and breaking up sedentary time as a viable strategy to improve glycemic control. PMID:28503154

Update on the X-Ray Variability Plane for Active Galactic Nuclei: The Role of the Obscuration

NASA Astrophysics Data System (ADS)

González-Martín, Omaira

2018-05-01

Scaling relations are the most powerful astrophysical tools to set constraints on the physical mechanisms of astronomical sources and to infer properties that cannot be accessed directly. We reinvestigate here one of these scaling relations in active galactic nuclei (AGNs); the so-called X-ray variability plane (or mass–luminosity timescale relation). This relation links the power-spectral density (PSD) break frequency with the super-massive black hole (SMBH) mass and the bolometric luminosity. We used the available XMM-Newton observations of a sample of 22 AGNs to study the PSD and spectra in short segments within each observation. This allows us to report for the first time that the PSD break frequency varies for each object, showing variations in 19 out of the 22 AGNs analyzed. Our analysis of the variability plane confirms the relation between the break frequency and the SMBH mass and finds that the obscuration along the line of sight N H (or the variations on the obscuration using its standard deviation, ΔN H) is also a required parameter, at least for the range of frequencies analyzed here (∼ 3 × {10}-5-5× {10}-2 {Hz}). We constrain a new variability plane of the following form: {log}({ν }Break})=(-0.589 +/- 0.005) {log}({{{M}}}BH})+(0.10+/- 0.01) {log}({{{N}}}{{H}})-(1.5+/- 0.3) (or {log}({ν }Break})=(-0.549+/- 0.009) {log}({{{M}}}BH}) +(0.56+/- 0.06) {{Δ }}{N}{{H}}+(0.19+/- 0.08)). The X-ray variability plane found by McHardy et al. is roughly recovered when we use unobscured segments. We speculate that this behavior is well explained if most of the reported frequencies are related to inner clouds (within 1 pc), following Kepler orbits under the gravitational field of the SMBH.

Tanned or burned: the role of fire in shaping physical seed dormancy.

PubMed

Moreira, Bruno; Pausas, Juli G

2012-01-01

Plant species with physical seed dormancy are common in mediterranean fire-prone ecosystems. Because fire breaks seed dormancy and enhances the recruitment of many species, this trait might be considered adaptive in fire-prone environments. However, to what extent the temperature thresholds that break physical seed dormancy have been shaped by fire (i.e., for post-fire recruitment) or by summer temperatures in the bare soil (i.e., for recruitment in fire-independent gaps) remains unknown. Our hypothesis is that the temperature thresholds that break physical seed dormancy have been shaped by fire and thus we predict higher dormancy lost in response to fire than in response to summer temperatures. We tested this hypothesis in six woody species with physical seed dormancy occurring in fire-prone areas across the Mediterranean Basin. Seeds from different populations of each species were subject to heat treatments simulating fire (i.e., a single high temperature peak of 100 °C, 120 °C or 150 °C for 5 minutes) and heat treatments simulating summer (i.e., temperature fluctuations; 30 daily cycles of 3 hours at 31 °C, 4 hours at 43 °C, 3 hours at 33 °C and 14 hours at 18 °C). Fire treatments broke dormancy and stimulated germination in all populations of all species. In contrast, summer treatments had no effect over the seed dormancy for most species and only enhanced the germination in Ulex parviflorus, although less than the fire treatments. Our results suggest that in Mediterranean species with physical dormancy, the temperature thresholds necessary to trigger seed germination are better explained as a response to fire than as a response to summer temperatures. The high level of dormancy release by the heat produced by fire might enforce most recruitment to be capitalized into a single post-fire pulse when the most favorable conditions occur. This supports the important role of fire in shaping seed traits.

Tanned or Burned: The Role of Fire in Shaping Physical Seed Dormancy

PubMed Central

Moreira, Bruno; Pausas, Juli G.

2012-01-01

Plant species with physical seed dormancy are common in mediterranean fire-prone ecosystems. Because fire breaks seed dormancy and enhances the recruitment of many species, this trait might be considered adaptive in fire-prone environments. However, to what extent the temperature thresholds that break physical seed dormancy have been shaped by fire (i.e., for post-fire recruitment) or by summer temperatures in the bare soil (i.e., for recruitment in fire-independent gaps) remains unknown. Our hypothesis is that the temperature thresholds that break physical seed dormancy have been shaped by fire and thus we predict higher dormancy lost in response to fire than in response to summer temperatures. We tested this hypothesis in six woody species with physical seed dormancy occurring in fire-prone areas across the Mediterranean Basin. Seeds from different populations of each species were subject to heat treatments simulating fire (i.e., a single high temperature peak of 100°C, 120°C or 150°C for 5 minutes) and heat treatments simulating summer (i.e., temperature fluctuations; 30 daily cycles of 3 hours at 31°C, 4 hours at 43°C, 3 hours at 33°C and 14 hours at 18°C). Fire treatments broke dormancy and stimulated germination in all populations of all species. In contrast, summer treatments had no effect over the seed dormancy for most species and only enhanced the germination in Ulex parviflorus, although less than the fire treatments. Our results suggest that in Mediterranean species with physical dormancy, the temperature thresholds necessary to trigger seed germination are better explained as a response to fire than as a response to summer temperatures. The high level of dormancy release by the heat produced by fire might enforce most recruitment to be capitalized into a single post-fire pulse when the most favorable conditions occur. This supports the important role of fire in shaping seed traits. PMID:23227267

[German National Physical Activity Recommendations for Adults and Older Adults: Methods, Database and Rationale].

PubMed

Füzéki, Eszter; Vogt, Lutz; Banzer, Winfried

2017-03-01

National physical activity recommendations are regarded as crucial elements of comprehensive physical activity promotion strategies. To date, Germany has no such national physical activity recommendations. The aim of this study was to provide physical activity recommendations based on a comprehensive summary of scientific evidence on the relationships between physical activity and a range of health outcomes in adults and older adults. The recommendations were developed in a 3-phase process (systematic literature review, development and use of quality criteria, synthesis of content) based on already existing high-quality guidelines. Based on the analysis of documents included in this study, the following recommendations were formulated. To gain wide-ranging health benefits, adults and older adults should be physically active regularly and avoid inactivity. Adults and older adults should carry out at least 150 min/week moderate intensity or 75 min/week high intensity aerobic activity. Adults and older adults can also reach the recommended amount of physical activity by performing activities in an appropriate combination in both intensity ranges. Optimally, physical activity should be distributed over the week and it can be accumulated in bouts of at least 10 min. Physical activity beyond 150 min/week yields further health benefits. At the same time, physical activity below 150 min/week is associated with meaningful health gains. Accordingly, all adults and older adults should be encouraged to be physically active whenever possible. Adults and older adults should also perform muscle strengthening activities at least twice a week. Regular balance exercises (3 times a week) can reduce the risk of falls in older adults. Adults and older adults should avoid long periods of sitting and should break up sitting time by physical activity. Physical activity can lead to adverse events, such as musculoskeletal injuries, which can be mitigated through appropriate measures. All in all, the benefits of regular physical activity overweigh by far the risks in both adults and older adults. © Georg Thieme Verlag KG Stuttgart · New York.

Laboratory studies on the excitation and collisional deactivation of metastable atoms and molecules in the aurora and airglow

NASA Technical Reports Server (NTRS)

Zipf, E. C.

1974-01-01

The aeronomy group at the University of Pittsburgh is actively engaged in a series of coordinated satellite, sounding rocket, and laboratory studies designed to expand and clarify knowledge of the physics and chemistry of planetary atmospheres. Three major discoveries have been made that will lead ultimately to a complete and dramatic revision of our ideas on the ionospheres of Mars, Venus, and the Earth and on the origin of their vacuum ultraviolet airglows. The results have already suggested a new generation of ionosphere studies which probably can be carried out best by laser heterodyning techniques. Laboratory studies have also identified, for the first time, the physical mechanism responsible for the remarkable nitric oxide buildup observed in some auroral arcs. This development is an important break-through in auroral physics, and has military ramifications of considerable interest to the Department of Defense. This work may also shed some light on related NO and atomic nitrogen problems in the mesosphere.

Symmetry-breaking Hopf bifurcations to 1-, 2-, and 3-tori in small-aspect-ratio counterrotating Taylor-Couette flow.

PubMed

Altmeyer, S; Do, Y; Marques, F; Lopez, J M

2012-10-01

The nonlinear dynamics of Taylor-Couette flow in a small-aspect-ratio wide-gap annulus in the counterrotating regime is investigated by solving the full three-dimensional Navier-Stokes equations. The system is invariant under arbitrary rotations about the axis, reflection about the annulus midplane, and time translations. A systematic investigation is presented both in terms of the flow physics elucidated from the numerical simulations and from a dynamical system perspective provided by equivariant normal form theory. The dynamics are primarily associated with the behavior of the jet of angular momentum that emerges from the inner cylinder boundary layer at about the midplane. The sequence of bifurcations as the differential rotation is increased consists of an axisymmetric Hopf bifurcation breaking the reflection symmetry of the basic state leading to an axisymmetric limit cycle with a half-period-flip spatiotemporal symmetry. This undergoes a Hopf bifurcation breaking axisymmetry, leading to quasiperiodic solutions evolving on a 2-torus that is setwise symmetric. These undergo a further Hopf bifurcation, introducing a third incommensurate frequency leading to a 3-torus that is also setwise symmetric. On the 3-torus, as the differential rotation is further increased, a saddle-node-invariant-circle bifurcation takes place, destroying the 3-torus and leaving a pair of symmetrically related 2-tori states on which all symmetries of the system have been broken.

Lyman Break Analogs: Constraints on the Formation of Extreme Starbursts at Low and High Redshift

NASA Technical Reports Server (NTRS)

Goncalves, Thiago S.; Overzier, Roderik; Basu-Zych, Antara; Martin, D. Christopher

2011-01-01

Lyman Break Analogs (LBAs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming galaxies in the low-redshift universe (z approximately equal to 0.2), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating the detailed study of LBAs as local laboratories of this high-redshift galaxy population. We present results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. We argue that such kinematic studies alone are not an appropriate diagnostic to rule out merger events as the trigger for the observed starburst. Comparison between the kinematic analysis and morphological indices from HST imaging illustrates the difficulties of properly identifying (minor or major) merger events, with no clear correlation between the results using either of the two methods. Artificial redshifting of our data indicates that this problem becomes even worse at high redshift due to surface brightness dimming and resolution loss. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We present preliminary results of a CARMA survey for LBAs and discuss the implications of the inferred molecular gas masses for formation models.

Rock Directed Breaking Under the Impulse Load

NASA Astrophysics Data System (ADS)

Khomeriki, Sergo; Mataradze, Edgar; Chikhradze, Nikoloz; Losaberidze, Marine; Khomeriki, Davit; Shatberashvili, Grigol

2016-10-01

In the work the problem of directed chipping of facing stone material by means of managing of explosion process is considered. The technology of the mining of decorative stone by the use of explosion energy means the very rapid transfer of potential energy of elastic deformations to kinetic energy. As a result, the explosion impulse, in the expanse of the inertia of rock massive, does not cause the increase of existing cracks. In the course of explosion, the shock wave is propagated by ultrasonic velocity and in this case the medium parameters (pressure, density, temperature, velocity) increase in spurts. In spite of this fact the all three conservation laws of mechanics remain valid on basis of three laws the equations are derived by which the parameters of shock wave may be defined by means of the rock physical-mechanical properties. The load on the body volume at breaking under explosion acts over very small period of the time. Therefore, stressed-deformed state of the rock was studied when the impulse load acts on the boundary. It was considered that the mining of the blocks of facing stone is performed from the hard rocks. This means that the breaking proceeds in the zone of elastic deformation. In the conditions of mentioned assumptions, the expression of the stress tensor and displacement of vector components initiated by stressed-deformed state in the rock are written.

Linear Collider Physics Resource Book for Snowmass 2001 - Part 3: Studies of Exotic and Standard Model Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abe, T.; et al.

This Resource Book reviews the physics opportunities of a next-generation e+e- linear collider and discusses options for the experimental program. Part 3 reviews the possible experiments on that can be done at a linear collider on strongly coupled electroweak symmetry breaking, exotic particles, and extra dimensions, and on the top quark, QCD, and two-photon physics. It also discusses the improved precision electroweak measurements that this collider will make available.

Effects of a DVD-delivered exercise program on patterns of sedentary behavior in older adults: a randomized controlled trial.

PubMed

Fanning, J; Porter, G; Awick, E A; Wójcicki, T R; Gothe, N P; Roberts, S A; Ehlers, D K; Motl, R W; McAuley, E

2016-06-01

In the present study, we examined the influence of a home-based, DVD-delivered exercise intervention on daily sedentary time and breaks in sedentary time in older adults. Between 2010 and 2012, older adults (i.e., aged 65 or older) residing in Illinois (N = 307) were randomized into a 6-month home-based, DVD-delivered exercise program (i.e., FlexToBa; FTB) or a waitlist control. Participants completed measurements prior to the first week (baseline), following the intervention period (month 6), and after a 6 month no-contact follow-up (month 12). Sedentary behavior was measured objectively using accelerometers for 7 consecutive days at each time point. Differences in daily sedentary time and breaks between groups and across the three time points were examined using mixed-factor analysis of variance (mixed ANOVA) and analysis of covariance (ANCOVA). Mixed ANOVA models revealed that daily minutes of sedentary time did not differ by group or time. The FTB condition, however, demonstrated a greater number of daily breaks in sedentary time relative to the control condition (p = .02). ANCOVA models revealed a non-significant effect favoring FTB at month 6, and a significant difference between groups at month 12 (p = .02). While overall sedentary time did not differ between groups, the DVD-delivered exercise intervention was effective for maintaining a greater number of breaks when compared with the control condition. Given the accumulating evidence emphasizing the importance of breaking up sedentary time, these findings have important implications for the design of future health behavior interventions.

Specific Physical Training in Elite Male Team Handball.

PubMed

Wagner, Herbert; Gierlinger, Manuel; Adzamija, Nermin; Ajayi, Samuel; Bacharach, David W; von Duvillard, Serge P

2017-11-01

Wagner, H, Gierlinger, M, Adzamija, N, Ajayi, S, Bacharach, DW, and von Duvillard, SP. Specific physical training in elite male team handball. J Strength Cond Res 31(11): 3083-3093, 2017-Specific physical training in elite team handball is essential for optimal player's performance; however, scientific knowledge is generally based on temporary training studies with subelite athletes. Therefore, the aim of the study was to analyze the effects of specific physical training in an elite male handball team over the entire season. Twelve players of a male handball team from the First Austrian Handball League conducted a 1-year specific physical training program in addition to their normal (team handball techniques and tactics) weekly training. Performance was measured with 5 general and 4 specific tests as well as game statistics during competition. Repeated measures analysis of variances and paired sample t-test were used to analyze differences in performance during training. We found a significant increase in oxygen uptake, offense time, defense time, fast break time, and jump height in the specific tests. Game performance statistics revealed a lower throwing percentage in the hosting team (59%) compared with the rival teams (63%). Our results indicated that specific endurance and agility are an acceptable modality in elite male team handball. However, performance in competition is strongly influenced by specific techniques and tactics. We recommend to strength and conditioning professionals that they tailor strength and power training, coordination and endurance as specific as possible, using free weights, agility exercises that include change in direction and jumps as well as short (10-15 seconds) high-intensity intervals.

9 CFR 590.522 - Breaking room operations.

Code of Federal Regulations, 2013 CFR

2013-01-01

... room personnel shall wash their hands thoroughly with odorless soap and water each time they enter the... wholesomeness by smelling the shell or the egg meat and by visual examination at the time of breaking. All egg... of shell particles and other foreign material shall be cleaned and sanitized each time it is...

9 CFR 590.522 - Breaking room operations.

Code of Federal Regulations, 2012 CFR

2012-01-01

... room personnel shall wash their hands thoroughly with odorless soap and water each time they enter the... wholesomeness by smelling the shell or the egg meat and by visual examination at the time of breaking. All egg... of shell particles and other foreign material shall be cleaned and sanitized each time it is...

9 CFR 590.522 - Breaking room operations.

Code of Federal Regulations, 2014 CFR

2014-01-01

... room personnel shall wash their hands thoroughly with odorless soap and water each time they enter the... wholesomeness by smelling the shell or the egg meat and by visual examination at the time of breaking. All egg... of shell particles and other foreign material shall be cleaned and sanitized each time it is...

Jet simulations and gamma-ray burst afterglow jet breaks

NASA Astrophysics Data System (ADS)

van Eerten, H. J.; Meliani, Z.; Wijers, R. A. M. J.; Keppens, R.

2011-01-01

The conventional derivation of the gamma-ray burst afterglow jet break time uses only the blast wave fluid Lorentz factor and therefore leads to an achromatic break. We show that in general gamma-ray burst afterglow jet breaks are chromatic across the self-absorption break. Depending on circumstances, the radio jet break may be postponed significantly. Using high-accuracy adaptive mesh fluid simulations in one dimension, coupled to a detailed synchrotron radiation code, we demonstrate that this is true even for the standard fireball model and hard-edged jets. We confirm these effects with a simulation in two dimensions. The frequency dependence of the jet break is a result of the angle dependence of the emission, the changing optical depth in the self-absorbed regime and the shape of the synchrotron spectrum in general. In the optically thin case the conventional analysis systematically overestimates the jet break time, leading to inferred opening angles that are underestimated by a factor of ˜1.3 and explosion energies that are underestimated by a factor of ˜1.7, for explosions in a homogeneous environment. The methods presented in this paper can be applied to adaptive mesh simulations of arbitrary relativistic fluid flows. All analysis presented here makes the usual assumption of an on-axis observer.

Gas transfer under high wind and its dependence on wave breaking and sea state

NASA Astrophysics Data System (ADS)

Brumer, Sophia; Zappa, Christopher; Fairall, Christopher; Blomquist, Byron; Brooks, Ian; Yang, Mingxi

2016-04-01

Quantifying greenhouse gas fluxes on regional and global scales relies on parameterizations of the gas transfer velocity K. To first order, K is dictated by wind speed (U) and is typically parameterized as a non-linear functions of U. There is however a large spread in K predicted by the traditional parameterizations at high wind speed. This is because a large variety of environmental forcing and processes (Wind, Currents, Rain, Waves, Breaking, Surfactants, Fetch) actually influence K and wind speed alone cannot capture the variability of air-water gas exchange. At high wind speed especially, breaking waves become a key factor to take into account when estimating gas fluxes. The High Wind Gas exchange Study (HiWinGS) presents the unique opportunity to gain new insights on this poorly understood aspects of air-sea interaction under high winds. The HiWinGS cruise took place in the North Atlantic during October and November 2013. Wind speeds exceeded 15 m s-1 25% of the time, including 48 hrs with U10 > 20 m s-1. Continuous measurements of turbulent fluxes of heat, momentum, and gas (CO2, DMS, acetone and methanol) were taken from the bow of the R/V Knorr. The wave field was sampled by a wave rider buoy and breaking events were tracked in visible imagery was acquired from the port and starboard side of the flying bridge during daylight hours at 20Hz. Taking advantage of the range of physical forcing and wave conditions sampled during HiWinGS, we test existing parameterizations and explore ways of better constraining K based on whitecap coverage, sea state and breaking statistics contrasting pure windseas to swell dominated periods. We distinguish between windseas and swell based on a separation algorithm applied to directional wave spectra for mixed seas, system alignment is considered when interpreting results. The four gases sampled during HiWinGS ranged from being mostly waterside controlled to almost entirely airside controlled. While bubble-mediated transfer appears to be small for moderately soluble gases like DMS, the importance of wave breaking turbulence transport has yet to be determined for all gases regardless of their solubility. This will be addressed by correlating measured K to estimates of active whitecap fraction (WA) and turbulent kinetic energy dissipation rate (ɛ). WA and ɛ are estimated from moments of the breaking crest length distribution derived from the imagery, focusing on young seas, when it is likely that large-scale breaking waves (i.e., whitecapping) will dominate the ɛ.

Analysis of free-time contingencies as positive versus negative reinforcement.

PubMed

Zarcone, J R; Fisher, W W; Piazza, C C

1996-01-01

Providing a short break contingent on completed work may increase responding through positive reinforcement (e.g., access to preferred activities) or negative reinforcement (e.g., escape form work). In this investigation, three analyses conducted with a boy with profound mental retardation showed that (a) a 20-s break increased responding more than a positive reinforcer (cola) did, and (b) the reinforcing effect of a 20-s break were affected by the availability of positive reinforcers during the break were affected by the availability of positive reinforcers during the break.

Comparison of vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification systems.

PubMed

Han, Young Keun; Miller, Kevin M

2009-08-01

To compare vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification machines. Jules Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. The vacuum rise time under normal and enhanced aspiration modes, vacuum limit accuracy, and occlusion break surge of the Infiniti Vision System, Stellaris Vision Enhancement System, and WhiteStar Signature Phacoemulsification System were tested. Vacuum rise time and limit accuracy were measured at limit settings of 400 mm Hg and 600 mm Hg. Surge area was recorded at vacuum limit settings of 200 mm Hg, 300 mm Hg, 400 mm Hg, and 500 mm Hg. The Infiniti had the fastest vacuum rise times under normal and enhanced aspiration modes. At 4 seconds, the vacuum limit accuracy was greatest with the Infiniti at the 400 mm Hg limit and the Signature at the 600 mm Hg limit. The Stellaris did not reach either vacuum target. The Infiniti performed better than the other 2 machines during testing of occlusion break surge at all vacuum limit settings above 200 mm Hg. Under controlled laboratory test conditions, the Infiniti had the fastest vacuum rise time, greatest vacuum limit accuracy at 400 mm Hg, and least occlusion break surge. These results can be explained by the lower compliance of the Infiniti system.

W.K.H. Panofsky Prize: The Long Journey to the Higgs Boson: CMS

NASA Astrophysics Data System (ADS)

Virdee, Tejinder

2017-01-01

There has been a rich harvest of physics from the experiments at the Large Hadron Collider (LHC). In July 2012, the ground-breaking discovery of the Higgs boson was made by the ATLAS and CMS experiments. This boson is a long-sought particle expected from the mechanism for spontaneous symmetry breaking in the electro-weak sector that provides an explanation of how elementary particles acquire mass. The discovery required experiments of unprecedented capability and complexity. This talk, complementing that of Peter Jenni, will trace the background to the search for the Higgs boson at the LHC, the conception, the construction and the operation of the CMS experiment, and its subsequent discovery of the boson. The SM is considered to be a low energy manifestation of a more complete theory - physics beyond the SM is therefore widely anticipated. Selected CMS results will be presented from the search for physics beyond the SM from the 13 TeV Run-2 at the LHC.

NSTX-U Advances in Real-Time C++11 on Linux

NASA Astrophysics Data System (ADS)

Erickson, Keith G.

2015-08-01

Programming languages like C and Ada combined with proprietary embedded operating systems have dominated the real-time application space for decades. The new C++11 standard includes native, language-level support for concurrency, a required feature for any nontrivial event-oriented real-time software. Threads, Locks, and Atomics now exist to provide the necessary tools to build the structures that make up the foundation of a complex real-time system. The National Spherical Torus Experiment Upgrade (NSTX-U) at the Princeton Plasma Physics Laboratory (PPPL) is breaking new ground with the language as applied to the needs of fusion devices. A new Digital Coil Protection System (DCPS) will serve as the main protection mechanism for the magnetic coils, and it is written entirely in C++11 running on Concurrent Computer Corporation's real-time operating system, RedHawk Linux. It runs over 600 algorithms in a 5 kHz control loop that determine whether or not to shut down operations before physical damage occurs. To accomplish this, NSTX-U engineers developed software tools that do not currently exist elsewhere, including real-time atomic synchronization, real-time containers, and a real-time logging framework. Together with a recent (and carefully configured) version of the GCC compiler, these tools enable data acquisition, processing, and output using a conventional operating system to meet a hard real-time deadline (that is, missing one periodic is a failure) of 200 microseconds.

Quantum break-time of de Sitter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dvali, Gia; Gómez, César; Zell, Sebastian, E-mail: georgi.dvali@physik.uni-muenchen.de, E-mail: cesar.gomez@uam.es, E-mail: sebastian.zell@campus.lmu.de

The quantum break-time of a system is the time-scale after which its true quantum evolution departs from the classical mean field evolution. For capturing it, a quantum resolution of the classical background—e.g., in terms of a coherent state—is required. In this paper, we first consider a simple scalar model with anharmonic oscillations and derive its quantum break-time. Next, following [1], we apply these ideas to de Sitter space. We formulate a simple model of a spin-2 field, which for some time reproduces the de Sitter metric and simultaneously allows for its well-defined representation as quantum coherent state of gravitons. Themore » mean occupation number N of background gravitons turns out to be equal to the de Sitter horizon area in Planck units, while their frequency is given by the de Sitter Hubble parameter. In the semi-classical limit, we show that the model reproduces all the known properties of de Sitter, such as the redshift of probe particles and thermal Gibbons-Hawking radiation, all in the language of quantum S -matrix scatterings and decays of coherent state gravitons. Most importantly, this framework allows to capture the 1/ N -effects to which the usual semi-classical treatment is blind. They violate the de Sitter symmetry and lead to a finite quantum break-time of the de Sitter state equal to the de Sitter radius times N . We also point out that the quantum-break time is inversely proportional to the number of particle species in the theory. Thus, the quantum break-time imposes the following consistency condition: older and species-richer universes must have smaller cosmological constants. For the maximal, phenomenologically acceptable number of species, the observed cosmological constant would saturate this bound if our Universe were 10{sup 100} years old in its entire classical history.« less

CN-110

EPA Pesticide Factsheets

Technical product bulletin: this surface washing agent for oil spill cleanups breaks the physical bond between the oil and the object to be cleaned (e.g., shoreline). Also use for herding or corralling a slick.

Lighten Up!

ERIC Educational Resources Information Center

Fleming, Colette

2001-01-01

Discusses how schools can reduce the occurances of physical injury, vandalism, and break-ins by properly lighting school areas. Several examples of lighting strategies are highlighted, including determining proper illumination levels for specific areas. (GR)

Effects of Classroom-Based Energizers on Primary Grade Students' Physical Activity Levels

ERIC Educational Resources Information Center

Bailey, Catherine Goffreda; DiPerna, James Clyde

2015-01-01

The primary aim of this study was to determine the effects of classroom-based exercise breaks (Energizers; Mahar, Kenny, Shields, Scales, & Collins, 2006) on students' physical activity levels during the school day. A multiple baseline design across first grade (N = 3) and second grade (N = 3) classrooms was used to examine the effects of the…

Feasibility and Effects of Short Activity Breaks for Increasing Preschool-Age Children's Physical Activity Levels

ERIC Educational Resources Information Center

Alhassan, Sofiya; Nwaokelemeh, Ogechi; Mendoza, Albert; Shitole, Sanyog; Puleo, Elaine; Pfeiffer, Karin A.; Whitt-Glover, Melicia C.

2016-01-01

Background: We examined the effects of short bouts of structured physical activity (SBS-PA) implemented within the classroom setting as part of designated gross-motor playtime on preschoolers PA. Methods: Preschools were randomized to SBS-PA (centers, N = 5; participants, N = 141) or unstructured free playtime (UPA) (centers, N = 5; participants,…

Probabilistic Round Trip Contamination Analysis of a Mars Sample Acquisition and Handling Process Using Markovian Decompositions

NASA Technical Reports Server (NTRS)

Hudson, Nicolas; Lin, Ying; Barengoltz, Jack

2010-01-01

A method for evaluating the probability of a Viable Earth Microorganism (VEM) contaminating a sample during the sample acquisition and handling (SAH) process of a potential future Mars Sample Return mission is developed. A scenario where multiple core samples would be acquired using a rotary percussive coring tool, deployed from an arm on a MER class rover is analyzed. The analysis is conducted in a structured way by decomposing sample acquisition and handling process into a series of discrete time steps, and breaking the physical system into a set of relevant components. At each discrete time step, two key functions are defined: The probability of a VEM being released from each component, and the transport matrix, which represents the probability of VEM transport from one component to another. By defining the expected the number of VEMs on each component at the start of the sampling process, these decompositions allow the expected number of VEMs on each component at each sampling step to be represented as a Markov chain. This formalism provides a rigorous mathematical framework in which to analyze the probability of a VEM entering the sample chain, as well as making the analysis tractable by breaking the process down into small analyzable steps.

Topological magnetoelectric effects in microwave far-field radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berezin, M.; Kamenetskii, E. O.; Shavit, R.

2016-07-21

Similar to electromagnetism, described by the Maxwell equations, the physics of magnetoelectric (ME) phenomena deals with the fundamental problem of the relationship between electric and magnetic fields. Despite a formal resemblance between the two notions, they concern effects of different natures. In general, ME-coupling effects manifest in numerous macroscopic phenomena in solids with space and time symmetry breakings. Recently, it was shown that the near fields in the proximity of a small ferrite particle with magnetic-dipolar-mode (MDM) oscillations have the space and time symmetry breakings and the topological properties of these fields are different from the topological properties of themore » free-space electromagnetic fields. Such MDM-originated fields—called magnetoelectric (ME) fields—carry both spin and orbital angular momenta. They are characterized by power-flow vortices and non-zero helicity. In this paper, we report on observation of the topological ME effects in far-field microwave radiation based on a small microwave antenna with a MDM ferrite resonator. We show that the microwave far-field radiation can be manifested with a torsion structure where an angle between the electric and magnetic field vectors varies. We discuss the question on observation of the regions of localized ME energy in far-field microwave radiation.« less

Shelf Sea Oxygen Dynamics: A year of Glider Measurements

NASA Astrophysics Data System (ADS)

Williams, C. A. J.; Palmer, M.; Mahaffey, C.; Jardine, J.

2016-02-01

Oxygen (O) is involved in most biogeochemical processes in the ocean, and dissolved oxygen (DO) is a well-established indicator for biological activity via the estimate of apparent oxygen utilisation (AOU). In the deep waters of the open ocean, the AOU provides a valuable insight into the ocean's biological carbon pump. However, in the physically dynamic and highly productive shallow shelf seas, interpretation of the O distribution and the magnitude of AOU is complex. Physical processes, such as diapycnal mixing, entrainment and horizontal advection act to ventilate waters below the thermocline and thus increase O and decrease AOU. In contrast, biological remineralisation of organic material below the thermocline will consume O and increase AOU. Here, we use 1 year of high-resolution data from >20 glider deployments in the seasonally stratified NW European Shelf Sea to identify and quantify the physical and biological processes that control the DO distribution and magnitude of AOU in shelf seas. A 200km transect between the shelf edge and the central Celtic Sea (CCS) was repeated between November 2014 and August 2015, thus capturing key periods in the seasonal cycling in shelf seas, specifically the onset of stratification, the spring bloom, stratified summer period and breakdown of stratification. The gliders collected data for DO, temperature, salinity, chlorophyll fluorescence, CDOM, backscatter and turbulence. In addition, direct measurements of turbulent dissipation from the Ocean Microstructure Glider deployed during the campaign provided estimates of mixing at CCS and the shelf break, allowing accurate quantification of the vertical fluxes of O. At the end of the stratified period the DO concentration was higher and AOU was lower at the shelf break (80 µM) compared to at CCS on shelf (>95 µM) (Fig 1). Estimates of vertical DO fluxes indicate that this horizontal variation in DO and AOU was partly attributed to enhanced mixing via internal waves at the shelf break ventilating waters below the thermocline, rather than decreased biological O consumption at the shelf break. Taking into consideration physical mixing processes, we provide a robust estimate of the biological O consumption over a seasonal cycle and highlight the need to consider the impact of physical processes on O dynamics in shallow shelf sea systems.

Standing Classrooms: Research and Lessons Learned from Around the World.

PubMed

Hinckson, Erica; Salmon, Jo; Benden, Mark; Clemes, Stacey A; Sudholz, Bronwyn; Barber, Sally E; Aminian, Saeideh; Ridgers, Nicola D

2016-07-01

Children spend between 50 and 70 % of their time sitting while at school. Independent of physical activity levels, prolonged sitting is associated with poor health outcomes in adulthood. While there is mixed evidence of health associations among children and adolescents, public health guidelines in the USA, UK, Australia and Canada now recommend young people should break up long periods of sitting as frequently as possible. A potentially effective approach for reducing and breaking up sitting throughout the day is changing the classroom environment. This paper presents an overview of a relatively new area of research designed to reduce youth sitting time while at school by changing the classroom environment (n = 13 studies). Environmental changes included placement of height-adjustable or stand-biased standing desks/workstations with stools, chairs, exercise balls, bean bags or mats in the classroom. These 13 published studies suggest that irrespective of the approach, youth sitting time was reduced by between ~44 and 60 min/day and standing time was increased by between 18 and 55 min/day during classroom time at school. Other benefits include increased energy expenditure and the potential for improved management of students' behaviour in the classroom. However, few large trials have been conducted, and there remains little evidence regarding the impact on children's learning and academic achievement. Nevertheless, with an increasing demand placed on schools and teachers regarding students' learning outcomes, strategies that integrate moving throughout the school day and that potentially enhance the learning experience and future health outcomes for young people warrant further exploration.

Dynamical evolution of differentiated asteroid families

NASA Astrophysics Data System (ADS)

Martins-Filho, W. S.; Carvano, J.; Mothe-Diniz, T.; Roig, F.

2014-10-01

The project aims to study the dynamical evolution of a family of asteroids formed from a fully differentiated parent body, considering family members with different physical properties consistent with what is expected from the break up of a body formed by a metallic nucleus surrounded by a rocky mantle. Initially, we study the effects of variations in density, bond albedo, and thermal inertia in the semi-major axis drift caused by the Yarkovsky effect. The Yarkovsky effect is a non-conservative force caused by the thermal re-radiation of the solar radiation by an irregular body. In Solar System bodies, it is known to cause changes in the orbital motions (Peterson, 1976), eventually bringing asteroids into transport routes to near-Earth space, such as some mean motion resonances. We expressed the equations of variation of the semi-major axis directly in terms of physical properties (such as the mean motion, frequency of rotation, conductivity, thermal parameter, specific heat, obliquity and bond albedo). This development was based on the original formalism for the Yarkovsky effect (i.e., Bottke et al., 2006 and references therein). The derivation of above equations allowed us to closely study the variation of the semi-major axis individually for each physical parameter, clearly showing that the changes in semi-major axis for silicate bodies is twice or three times greater than for metal bodies. The next step was to calculate the orbital elements of a synthetic family after the break-up. That was accomplished assuming that the catastrophic disruption energy is given by the formalism described by Stewart and Leinhardt (2009) and assuming an isotropic distribution of velocities for the fragments of the nucleus and the mantle. Finally, the orbital evolution of the fragments is implemented using a simpletic integrator, and the result compared with the distribution of real asteroid families.

Acute Effect of Intermittent Exercise and Action-Based Video Game Breaks on Math Performance in Preadolescent Children.

PubMed

Block, Shannon S; Tooley, Trevor R; Nagy, Matthew R; O'Sullivan, Molly P; Robinson, Leah E; Colabianchi, Natalie; Hasson, Rebecca E

2018-02-27

The purpose of this study was to compare the acute effects of video game breaks and intermittent exercise breaks, performed at varying intensities, on math performance in preadolescent children. A total of 39 children (18 males and 21 females; aged 7-11 y) completed 4 experimental conditions in random order: 8 hours of sitting interrupted with 20 two-minute low-, moderate-, or high-intensity exercise breaks or 20 two-minute sedentary computer game breaks. The intensity of exercise breaks for the low-, moderate-, and high-intensity conditions corresponded with 25%, 50%, and 75% of heart rate reserve, respectively. Math performance was assessed 3 times throughout each condition day using a 90-second math test consisting of 40 single-digit addition and subtraction questions. There were no significant differences in percent change in math scores (correct answers out of attempted) by condition [low: -1.3 (0.8), moderate: 0.1 (1.3), high: -1.8 (0.7), and computer: -2.5 (0.8); P > .05]. There were significant differences in percent change in math scores over the course of the condition days with lower math scores reported at end-of-day test compared with midday test [-2.4 (0.5) vs -0.4 (0.3); P = .01]. There were no significant condition × time, time × age, condition × age, or condition × time × age interactions (all Ps > .05). Action-based video game and exercise breaks elicit the same level of math performance in children; however, time of day may impact this relationship. These findings may have important implications for instructional time in elementary classrooms.

Accelerometer profiles of physical activity and inactivity in normal weight, overweight, and obese U.S. men and women.

PubMed

Tudor-Locke, Catrine; Brashear, Meghan M; Johnson, William D; Katzmarzyk, Peter T

2010-08-03

The 2005-2006 National Health and Nutrition Examination Survey (NHANES) is used to describe an accelerometer-derived physical activity/inactivity profile in normal weight (BMI < 25 kg/m2), overweight (25 /= 30 kg/m2) U.S. adults. We computed physical activity volume indicators (activity counts/day, uncensored and censored steps/day), rate indicators (e.g., steps/minute), time indicators (employing NHANES activity counts/minute cut points to infer time in non-wear, sedentary, low, light, moderate, and vigorous intensities), the number of breaks in sedentary time (occasions when activity counts rose from < 100 activity/counts in one minute to >/= 100 activity counts in the subsequent minute), achievement of public health guidelines, and classification by step-defined physical activity levels. Data were examined for evidence of consistent and significant gradients across BMI-defined categories. In 2005-2006, U.S adults averaged 6,564 +/- SE 107 censored steps/day, and after considering non-wear time, they spent approximately 56.8% of the rest of the waking day in sedentary time, 23.7% in low intensity, 16.7% in light intensity, 2.6% in moderate intensity, and 0.2% in vigorous intensity. Overall, approximately 3.2% of U.S. adults achieved public health guidelines. The normal weight category took 7,190 +/- SE 157 steps/day, and spent 25.7 +/- 0.9 minutes/day in moderate intensity and 7.3 +/- 0.4 minutes/day in vigorous intensity physical activity. The corresponding numbers for the overweight category were 6,879 +/- 140 steps/day, 25.3 +/- 0.9 minutes/day, and 5.3 +/- 0.5 minutes/day and for the obese category 5,784 +/- 124 steps/day, 17.3 +/- 0.7 minutes/day and 3.2 +/- 0.4 minutes/day. Across BMI categories, increasing gradients and significant trends were apparent in males for sedentary time and decreasing gradients and significant trends were evident in time spent in light intensity, moderate intensity, and vigorous intensity. For females, there were only consistent gradients and significant trends apparent for decreasing amounts of time spent in moderate and vigorous intensity. Simple indicators of physical activity volume (i.e., steps/day) and time in light, moderate or vigorous intensity physical activity differ across BMI categories for both sexes, suggesting that these should continue to be targets for surveillance.

Half-time strategies to enhance second-half performance in team-sports players: a review and recommendations.

PubMed

Russell, Mark; West, Daniel J; Harper, Liam D; Cook, Christian J; Kilduff, Liam P

2015-03-01

A number of intermittent team sports require that two consecutive periods of play (lasting for ~30-45 min) are separated by a 10-20 min half-time break. The half-time practices employed by team-sports players generally include returning to the changing rooms, temporarily relaxing from the cognitive and physical demands of the first half, rehydration and re-fuelling strategies, addressing injury or equipment concerns, and receiving tactical instruction and coach feedback. However, the typically passive nature of these actions has been associated with physiological changes that impair performance during the second half. Both physical and cognitive performances have been found to decline in the initial stages of subsequent exercise that follows half-time. An increased risk of injury has also been observed during this period. Therefore, half-time provides sports scientists and strength and conditioning coaches with an opportunity to optimise second-half performance. An overview of strategies thought to benefit team-sports athletes is presented; specifically, the efficacy of heat maintenance strategies (including passive and active methods), post-activation potentiation, hormonal priming, and modified hydro-nutritional practices are discussed. A theoretical model of applying these strategies in a manner that compliments current practice is also offered.

The role of puberty in the making and breaking of young ballet dancers: Perspectives of dance teachers.

PubMed

Mitchell, Siobhan B; Haase, Anne M; Malina, Robert M; Cumming, Sean P

2016-02-01

Physical changes associated with puberty may conflict with functional and aesthetic ideals for a career in ballet. The dance teacher is in a position to guide young dancers through the pubertal transition, although dancers rather than teachers are often the focus of research. This study explores the social stimulus value of the female body in ballet as perceived by the dance teacher and how value may change during puberty. Ten UK dance teachers were interviewed; interpretative phenomenological analysis was used. Four main themes perceived by dance teachers emerged as central to the social stimulus value of the body among adolescent dancers: the ideal body; teacher approaches to managing puberty in the dance environment; puberty as a 'make or break' stage in ballet; and teacher awareness of pubertal onset and the implications of timing. Dance teachers can play an important role in moderating external and individual expectations during the pubertal transition. Copyright © 2015 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.

Nodeless superconductivity and time-reversal symmetry breaking in the noncentrosymmetric superconductor Re24Ti5

NASA Astrophysics Data System (ADS)

Shang, T.; Pang, G. M.; Baines, C.; Jiang, W. B.; Xie, W.; Wang, A.; Medarde, M.; Pomjakushina, E.; Shi, M.; Mesot, J.; Yuan, H. Q.; Shiroka, T.

2018-01-01

The noncentrosymmetric superconductor Re24Ti5 , a time-reversal symmetry- (TRS-) breaking candidate with Tc=6 K , was studied by means of muon-spin rotation/relaxation (μ SR ) and tunnel-diode oscillator techniques. At the macroscopic level, its bulk superconductivity was investigated via electrical resistivity, magnetic susceptibility, and heat-capacity measurements. The low-temperature penetration depth, superfluid density, and electronic heat capacity all evidence an s -wave coupling with an enhanced superconducting gap. The spontaneous magnetic fields revealed by zero-field μ SR below Tc indicate a time-reversal symmetry breaking and thus the unconventional nature of superconductivity in Re24Ti5 . The concomitant occurrence of TRS breaking also in the isostructural Re6(Zr ,Hf ) compounds hints at its common origin in this superconducting family and that an enhanced spin-orbital coupling does not affect pairing symmetry.

The Record Los Angeles Heat Event of September 2010: 1. Synoptic-Scale-Meso-β-Scale Analyses of Interactive Planetary Wave Breaking, Terrain- and Coastal-Induced Circulations

NASA Astrophysics Data System (ADS)

Kaplan, Michael L.; Tilley, Jeffrey S.; Hatchett, Benjamin J.; Smith, Craig M.; Walston, Joshua M.; Shourd, Kacie N.; Lewis, John M.

2017-10-01

On 27 September 2010 the Los Angeles Civic Center reached its all-time record maximum temperature of 45°C before 1330 local daylight time with several other regional stations observing all-time record breaking heat early in that afternoon. This record event is associated with a general circulation pattern predisposed to hemispheric wave breaking. Three days before the event, wave breaking organizes complex terrain- and coastal-induced processes that lead to isentropic surface folding into the Los Angeles Basin. The first wave break occurs over the western two thirds of North America leading to trough elongation across the southwestern U.S. Collocated with this trough is an isentropic potential vorticity filament that is the locus of a thermally indirect circulation central to warming and associated thickness increases and ridging westward across the Great Basin. In response to this circulation, two subsynoptic wave breaks are triggered along the Pacific coast. The isentropic potential vorticity filament is coupled to the breaking waves and the interaction produces a subsynoptic low-pressure center and a deep vortex aloft over the southeastern California desert. This coupling leads to advection of an elevated mixed layer over Point Conception the night before the record-breaking heat that creates a coastally trapped low-pressure area southwest of Los Angeles. The two low-pressure centers create a low-level pressure gradient and east-southeasterly jet directed offshore over the Los Angeles Basin by sunrise on 27 September. This allows the advection of low-level warm air from the inland terrain toward the coastally trapped disturbance and descending circulation resulting in record heating.

Remote Sensing Characterization of Two-dimensional Wave Forcing in the Surf Zone

NASA Astrophysics Data System (ADS)

Carini, R. J.; Chickadel, C. C.; Jessup, A. T.

2016-02-01

In the surf zone, breaking waves drive longshore currents, transport sediment, shape bathymetry, and enhance air-sea gas and particle exchange. Furthermore, wave group forcing influences the generation and duration of rip currents. Wave breaking exhibits large gradients in space and time, making it challenging to measure in situ. Remote sensing technologies, specifically thermal infrared (IR) imagery, can provide detailed spatial and temporal measurements of wave breaking at the water surface. We construct two-dimensional maps of active wave breaking from IR imagery collected during the Surf Zone Optics Experiment in September 2010 at the US Army Corps of Engineers' Field Research Facility in Duck, NC. For each breaker identified in the camera's field of view, the crest-perpendicular length of the aerated breaking region (roller length) and wave direction are estimated and used to compute the wave energy dissipation rate. The resultant dissipation rate maps are analyzed over different time scales: peak wave period, infragravity wave period, and tidal wave period. For each time scale, spatial maps of wave breaking are used to characterize wave forcing in the surf zone for a variety of wave conditions. The following phenomena are examined: (1) wave dissipation rates over the bar (location of most intense breaking) have increased variance in infragravity wave frequencies, which are different from the peak frequency of the incoming wave field and different from the wave forcing variability at the shoreline, and (2) wave forcing has a wider spatial distribution during low tide than during high tide due to depth-limited breaking over the barred bathymetry. Future work will investigate the response of the variability in wave setup, longshore currents and rip currents, to the variability in wave forcing in the surf zone.

Predicting Tissue Breaking Strengths in the Epileptic Brain with T2 Relaxometry: Application of Pulsed Water Jet Dissection System for Epilepsy Surgery.

PubMed

Takahashi, Yoko; Iwasaki, Masaki; Nakagawa, Atsuhiro; Sato, Shiho; Nakasato, Nobukazu; Tominaga, Teiji

2017-11-01

Background  The piezo actuator-driven pulsed water jet (ADPJ) system is a novel surgical instrument that enables dissection of tissue without thermal damage. Using the ADPJ system in epilepsy surgery requires prediction of the tissue breaking strength of the epileptic brain. The aim of this study was to elucidate whether magnetic resonance imaging T2 relaxometry could predict the breaking strength. Methods  A total of 12 patients with drug-resistant temporal lobe epilepsy who received surgical treatment were included in the study. All the patients qualified for surgery after a comprehensive preoperative evaluation for the treatment of epilepsy. T2 relaxation time, breaking strength of the hippocampus, and an anterior temporal lobe specimen obtained from surgery with dissection depth determined by the ADPJ system were examined. Results  Preoperative T2 relaxation times of the anterior temporal lobe and hippocampus showed mild positive correlation with breaking strength (R 2  = 0.60). The hippocampus showed higher T2 relaxation time than the temporal lobe. Hippocampal sclerosis seemed to have higher breaking strength than other pathologies, suggesting the correlation depends on the anatomical location and histopathology. The dissection depth of the extirpated lesion was negatively correlated with the breaking strength at input voltages of 10 V (R 2  = - 0.34) and 20 V (R 2  = - 0.20). Conclusions  T2 relaxometry may be useful to predict tissue breaking strength in the epileptic brain that allows safe application of the ADPJ system in epilepsy surgery. Georg Thieme Verlag KG Stuttgart · New York.

Habitual physical activity in mitochondrial disease.

PubMed

Apabhai, Shehnaz; Gorman, Grainne S; Sutton, Laura; Elson, Joanna L; Plötz, Thomas; Turnbull, Douglass M; Trenell, Michael I

2011-01-01

Mitochondrial disease is the most common neuromuscular disease and has a profound impact upon daily life, disease and longevity. Exercise therapy has been shown to improve mitochondrial function in patients with mitochondrial disease. However, no information exists about the level of habitual physical activity of people with mitochondrial disease and its relationship with clinical phenotype. Habitual physical activity, genotype and clinical presentations were assessed in 100 patients with mitochondrial disease. Comparisons were made with a control group individually matched by age, gender and BMI. Patients with mitochondrial disease had significantly lower levels of physical activity in comparison to matched people without mitochondrial disease (steps/day; 6883±3944 vs. 9924±4088, p = 0.001). 78% of the mitochondrial disease cohort did not achieve 10,000 steps per day and 48% were classified as overweight or obese. Mitochondrial disease was associated with less breaks in sedentary activity (Sedentary to Active Transitions, % per day; 13±0.03 vs. 14±0.03, p = 0.001) and an increase in sedentary bout duration (bout lengths/fraction of total sedentary time; 0.206±0.044 vs. 0.187±0.026, p = 0.001). After adjusting for covariates, higher physical activity was moderately associated with lower clinical disease burden (steps/day; r(s) = -0.49; 95% CI -0.33, -0.63, P<0.01). There were no systematic differences in physical activity between different genotypes mitochondrial disease. These results demonstrate for the first time that low levels of physical activity are prominent in mitochondrial disease. Combined with a high prevalence of obesity, physical activity may constitute a significant and potentially modifiable risk factor in mitochondrial disease.

Which homogenisation method is appropriate for daily time series of relative humidity?

NASA Astrophysics Data System (ADS)

Chimani, Barbara; Nemec, Johanna; Auer, Ingeborg; Venema, Victor

2014-05-01

Data homogenisation is an essential part of reliable climate data analyses. Different tools for detecting and adjusting breaks in daily extreme temperatures (Tmin, Tmax) and daily precipitation sums were developed in the last years. Due to its influence on health, plants and construction relative humidity is another parameter of great importance. On the basis of 6 networks of measured (and homogenized with respect to the monthly means) relative humidity data, which cover different climatic areas in Austria, a synthetic data set for testing and validating homogenisation methods was built. Each network consists of 4 to 6 station time series with a minimum length of 5 years. The so-called surrogate networks resemble the statistical properties (e.g. distribution of parameter, auto- and cross correlation within the network) of the measured time series, but are extended to 100 year long time series, which are in a first step assumed to be homogeneous. For creating the best possible surrogate dataset of relative humidity detailed statistical information on potential inhomogeneities is decisive. Information on the potential breaks was taken from parallel measurements available for some Austrian locations, mostly representing changes in instrumentation and/or station relocation. Beside changes in the distribution of the parameter the analyses includes an estimation of changes in the number of missing data, global and local biases, both on a seasonal and annual basis. An additional break is to be expected in the Austrian time series due to a change in observation time in 1970/1971. Since this change occurred simultaneously at all Austrian climate stations, standard homogenisation methods, which rely on a comparison with reference stations, are not able to detect or correct this shift. Therefore an independent correction method for this type of break, to be applied before homogenisation was developed. This type of change point was not included in the surrogate network. Artificial inhomogenities were introduced to the dataset in three steps: (1) deterministic change points: within one homogeneous sub-period (HSP) a constant perturbation is added to each relative humidity values, (2) deterministic + random changes: random changes do not change the mean of the HSP but can affect the distribution of the parameter, (3) in addition realistic changes in break frequency and missing data. In order to tests the efficiency of homogenisation methods, the procedure was separated in break detection and adjustment of inhomogenities. The methods MASH (Szentimrey, 1999), ACMANT (Domonkos, 2011), PRODIGE (Caussinus and Mestre, 2004), SNHT (Alexandersson, 1986), Vincent (Vincent, 1998), E-P method (Easterling and Peterson, 1995) and Bivariate test (Maronna and Yohai, 1978) were selected for break detection. Break detection is in all methods restricted to monthly, seasonal or annual data. Since we are dealing with daily data, the amount of methods for break correction is reduced and we concentrate on the following methods: MASH, Vincent, SPLIDHOM (Mestre et al., 2011) and the percentile method (Stepanek, 2009). Information on the statistical characteristics of breaks in relative humidity series, the correction method concerning the changed observation times and first results concerning break detection will be presented.

Camden active spaces: does the construction of active school playgrounds influence children's physical activity levels? A longitudinal quasi-experiment protocol.

PubMed

Smith, Lee; Kipps, Courtney; Aggio, Daniel; Fox, Paul; Robinson, Nigel; Trend, Verena; Munnery, Suzie; Kelly, Barry; Hamer, Mark

2014-01-01

Physical activity is essential for every facet of children's health. However, physical activity levels in British children are low. The school environment is a promising setting to increase children's physical activity but limited empirical evidence exists on how a change in the outdoor physical school environment influences physical activity behaviour. The London Borough of Camden is redesigning seven existing school playgrounds to engage children to become more physically active. The primary aim of this project is to evaluate the impact of the redesigned playgrounds on children's physical activity, well-being and physical function/fitness. This project will use a longitudinal quasi-experimental design. Seven experimental schools and one control school will take part. One baseline data collection session and two follow-ups will be carried out. Between baseline and follow-up, the experimental school playgrounds will be redesigned. At baseline, a series of fitness tests, anthropometric and questionnaire measurements, and 7-day objective physical activity monitoring (Actigraph accelerometer) will be carried out on children (aged 5–16 years). This will be repeated at follow-up. Changes in overall physical activity levels and levels during different times of the day (eg, school breaks) will be examined. Multilevel regression modelling will be used to analyse the data. The results of this study will be disseminated through peer-review publications and scientific presentations. Ethical approval was obtained through the University College London Research Ethics Committee (Reference number: 4400/002).

Towards a Molecular Movie: Real Time Observation of Hydrogen Bond Breaking by Transient 2D-IR Spectroscopy in a Cyclic Peptide

NASA Astrophysics Data System (ADS)

Kolano, Christoph; Helbing, Jan; Sander, Wolfram; Hamm, Peter

Transient two-dimensional infrared spectroscopy (T2D-IR) has been used to observe in real time the non-equilibrium structural dynamics of intramolecular hydrogen bond breaking in a small cyclic disulfide-bridged peptide.

Physical inactivity and sedentary behavior: Overlooked risk factors in autoimmune rheumatic diseases?

PubMed

Pinto, Ana Jéssica; Roschel, Hamilton; de Sá Pinto, Ana Lúcia; Lima, Fernanda Rodrigues; Pereira, Rosa Maria Rodrigues; Silva, Clovis Artur; Bonfá, Eloisa; Gualano, Bruno

2017-07-01

This review aims to (1) summarize the estimates of physical inactivity and sedentary behavior in autoimmune rheumatic diseases; (2) describe the relationship between physical (in)activity levels and disease-related outcomes; (3) contextualize the estimates and impact of physical inactivity and sedentary behavior in autoimmune diseases compared to other rheumatic diseases and chronic conditions; and (4) discuss scientific perspectives around this theme and potential clinical interventions to attenuate these preventable risk factors. We compiled evidence to show that estimates of physical inactivity and sedentary behavior in autoimmune rheumatic diseases are generally comparable to other rheumatic diseases as well as to other chronic conditions (e.g., type 2 diabetes, cardiovascular diseases, and obesity), in which a lack of physical activity and excess of sedentary behavior are well-known predictors of morbimortality. In addition, we also showed evidence that both physical inactivity and sedentary behavior may be associated with poor health-related outcomes (e.g., worse disease symptoms and low functionality) in autoimmune rheumatic diseases. Thus, putting into practice interventions to make the patients "sit less and move more", particularly light-intensity activities and/or breaking-up sedentary time, is a simple and prudent therapeutic approach to minimize physical inactivity and sedentary behavior, which are overlooked yet modifiable risk factors in the field of autoimmune rheumatic diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Refined Source Terms in Wave Watch 3 with Wave Breaking and Sea Spray Forecasts

DTIC Science & Technology

2016-08-05

Farmer at IOS Canada involved a novel scale analysis of breaking waves. This was motivated by the results of the model study of wave breaking onset by...timely development that needs careful examination. 4.11 Highlights of the SPANDEX study SPANDEX, the Spray Production and Dynamics Experiment, is...speed alone. To accomplish this goal, a parallel laboratory study (SPANDEX II) was undertaken to parameterize sea spray flux dependences on breaking

J. J. Sakurai Prize for Theoretical Particle Physics Talk: The Boundless Horizons of Supercollider Physics

NASA Astrophysics Data System (ADS)

Quigg, Chris

2011-04-01

The Large Hadron Collider at CERN is moving the experimental frontier of particle physics to the domain of electroweak symmetry breaking, reaching energies around one trillion electron volts for collisions among the basic constituents of matter. We do not know what the new wave of exploration will find, but the discoveries we make and the new puzzles we encounter are certain to change the face of particle physics and echo through neighboring sciences. In this new world, we confidently expect to learn what sets electromagnetism apart from the weak interactions, with profound implications for deceptively simple questions: Why are there atoms? Why chemistry? What makes stable structures possible? A pivotal step will be finding the Higgs boson-or whatever takes its place -and exploring its properties. But we hope for much more. More predictive extensions of the electroweak theory, including dynamical symmetry breaking and supersymmetry, imply new kinds of matter that would be within reach of LHC experiments. We suspect that candidates for the dark matter of the Universe could also await discovery on the TeV scale. The strong interactions may hold their own surprises. As we unravel the riddle of electroweak symmetry breaking, prospects arise for other new insights: into the different forms of matter, the unity of quarks and leptons, and the nature of spacetime. The questions in play all seem linked to one another-and to the kinship of the weak and electromagnetic interactions. I will speak of the evolving dialogue between theory and experiment, highlighting the work before us. Fermilab is operated by the Fermi Research Alliance under contract no. DE-AC02-07CH11359 with the U.S. Department of Energy.

Fibre Break Failure Processes in Unidirectional Composites. Part 2: Failure and Critical Damage State Induced by Sustained Tensile Loading

NASA Astrophysics Data System (ADS)

Thionnet, A.; Chou, H. Y.; Bunsell, A.

2015-04-01

The purpose of these three papers is not to just revisit the modelling of unidirectional composites. It is to provide a robust framework based on physical processes that can be used to optimise the design and long term reliability of internally pressurised filament wound structures. The model presented in Part 1 for the case of monotonically loaded unidirectional composites is further developed to consider the effects of the viscoelastic nature of the matrix in determining the kinetics of fibre breaks under slow or sustained loading. It is shown that the relaxation of the matrix around fibre breaks leads to locally increasing loads on neighbouring fibres and in some cases their delayed failure. Although ultimate failure is similar to the elastic case in that clusters of fibre breaks ultimately control composite failure the kinetics of their development varies significantly from the elastic case. Failure loads have been shown to reduce when loading rates are lowered.

Fragmentation of an elastica

NASA Astrophysics Data System (ADS)

Vandenberghe, Nicolas; Villermaux, Emmanuel

2009-03-01

When a thin rod is submitted to an axial force greater than its critical buckling load it takes the shape of an elastica. As the load further increases, a rod made of a brittle material breaks suddenly. More than two fragments may be formed during this fragmentation. In this work we discuss the sequence of events that lead to the final broken state with two or more fragments. We show that the criterion for breaking is not trivial. In particular, we investigate the effect of the duration of the loading and we show that at a given load the waiting time before breaking is broadly distributed. We discuss the consequences of the time delayed breaking on the distributions of fragment sizes and fragment numbers.

Focus, locus, and sensus: the three dimensions of virtual experience.

PubMed

Waterworth, E L; Waterworth, J A

2001-04-01

A model of virtual/physical experience is presented, which provides a three dimensional conceptual space for virtual and augmented reality (VR and AR) comprising the dimensions of focus, locus, and sensus. Focus is most closely related to what is generally termed presence in the VR literature. When in a virtual environment, presence is typically shared between the VR and the physical world. "Breaks in presence" are actually shifts of presence away from the VR and toward the external environment. But we can also have "breaks in presence" when attention moves toward absence--when an observer is not attending to stimuli present in the virtual environment, nor to stimuli present in the surrounding physical environment--when the observer is present in neither the virtual nor the physical world. We thus have two dimensions of presence: focus of attention (between presence and absence) and the locus of attention (the virtual vs. the physical world). A third dimension is the sensus of attention--the level of arousal determining whether the observer is highly conscious or relatively unconscious while interacting with the environment. After expanding on each of these three dimensions of experience in relation to VR, we present a couple of educational examples as illustrations, and also relate our model to a suggested spectrum of evaluation methods for virtual environments.

Coupled-channel approach to strangeness S = -2 baryon-bayron interactions in lattice QCD

NASA Astrophysics Data System (ADS)

Sasaki, Kenji; Aoki, Sinya; Doi, Takumi; Hatsuda, Tetsuo; Ikeda, Yoichi; Inoue, Takashi; Ishii, Noriyoshi; Murano, Keiko

2015-11-01

Baryon-baryon interactions with strangeness S=-2 with flavor SU(3) breaking are calculated for the first time by using the HAL QCD method extended to the coupled-channel system in lattice QCD. The potential matrices are extracted from the Nambu-Bethe-Salpeter wave functions obtained by the 2+1-flavor gauge configurations of the CP-PACS/JLQCD Collaborations with a physical volume of (1.93 fm)^3 and with m_{π }/m_K=0.96, 0.90, 0.86. The spatial structure and the quark mass dependence of the potential matrix in the baryon basis and in the SU(3) basis are investigated.

A Macroscopic Approach to the Lane Formation Phenomenon in Pedestrian Counterflow

NASA Astrophysics Data System (ADS)

Xiong, Tao; Zhang, Peng; Wong, S. C.; Shu, Chi-Wang; Zhang, Meng-Ping

2011-10-01

We simulate pedestrian counterflow by adopting an optimal path-choice strategy and a recently observed speed-density relationship. Although the whole system is symmetric, the simulation demonstrates the segregation and formation of many walking lanes for two groups of pedestrians. The symmetry breaking is most likely triggered by a small numerical viscosity or “noise", and the segregation is associated with the minimization of travel time. The underlying physics can be compared with the “optimal self-organization" mechanism in Helbing's social force model, by which driven entities in an open system tend to minimize their interaction to enable them to reach some ordering state.

Symmetry breaking in clogging for oppositely driven particles

NASA Astrophysics Data System (ADS)

Glanz, Tobias; Wittkowski, Raphael; Löwen, Hartmut

2016-11-01

The clogging behavior of a symmetric binary mixture of colloidal particles that are driven in opposite directions through constrictions is explored by Brownian dynamics simulations and theory. A dynamical state with a spontaneously broken symmetry occurs where one species is flowing and the other is blocked for a long time, which can be tailored by the size of the constrictions. Moreover, we find self-organized oscillations in clogging and unclogging of the two species. Apart from statistical physics, our results are of relevance for fields like biology, chemistry, and crowd management, where ions, microparticles, pedestrians, or other particles are driven in opposite directions through constrictions.

Effect of pressure on rate of burning /decomposition with flame/ of liquid hydrazine.

NASA Technical Reports Server (NTRS)

Antoine, A. C.

1966-01-01

Liquid hydrazine decomposition process to determine what chemical or physical changes may be occurring that cause breaks in burning rate/ pressure curves, measuring flame temperature and light emission

Petroleum Oils

EPA Pesticide Factsheets

Different types of crude oil and refined product, of all different chemical compositions, have distinct physical properties. These properties affect the way oil spreads and breaks down, its hazard to marine and human life, and the likelihood of threat.

Probing the scale of new physics by Advanced LIGO/VIRGO

NASA Astrophysics Data System (ADS)

Dev, P. S. Bhupal; Mazumdar, A.

2016-05-01

We show that if the new physics beyond the standard model is associated with a first-order phase transition around 107- 108 GeV , the energy density stored in the resulting stochastic gravitational waves and the corresponding peak frequency are within the projected final sensitivity of the advanced LIGO/VIRGO detectors. We discuss some possible new physics scenarios that could arise at such energies, and in particular, the consequences for Peccei-Quinn and supersymmetry breaking scales.

Thermalization and light cones in a model with weak integrability breaking

DOE PAGES

Bertini, Bruno; Essler, Fabian H. L.; Groha, Stefan; ...

2016-12-09

Here, we employ equation-of-motion techniques to study the nonequilibrium dynamics in a lattice model of weakly interacting spinless fermions. Our model provides a simple setting for analyzing the effects of weak integrability-breaking perturbations on the time evolution after a quantum quench. We establish the accuracy of the method by comparing results at short and intermediate times to time-dependent density matrix renormalization group computations. For sufficiently weak integrability-breaking interactions we always observe prethermalization plateaus, where local observables relax to nonthermal values at intermediate time scales. At later times a crossover towards thermal behavior sets in. We determine the associated time scale,more » which depends on the initial state, the band structure of the noninteracting theory, and the strength of the integrability-breaking perturbation. Our method allows us to analyze in some detail the spreading of correlations and in particular the structure of the associated light cones in our model. We find that the interior and exterior of the light cone are separated by an intermediate region, the temporal width of which appears to scale with a universal power law t 1/3.« less

Impact of Short Duration Health & Science Energizers in the Elementary School Classroom

ERIC Educational Resources Information Center

Raney, Marcella; Henriksen, Adriel; Minton, Jessica; Lynch, Timothy Joseph

2017-01-01

Background: Acute physical activity breaks lasting 10--60 min have been related to positive effects on student focus and academic performance. The aim of this study was to evaluate the impact of repeated brief physical activity-infused academic lessons (1-5 min) on student retention and on-task behavior. Methods: One class from each K-2 grade…

Breaking the Code: The Creative Use of QR Codes to Market Extension Events

ERIC Educational Resources Information Center

Hill, Paul; Mills, Rebecca; Peterson, GaeLynn; Smith, Janet

2013-01-01

The use of smartphones has drastically increased in recent years, heralding an explosion in the use of QR codes. The black and white square barcodes that link the physical and digital world are everywhere. These simple codes can provide many opportunities to connect people in the physical world with many of Extension online resources. The…

Perceived Barriers and Facilitators to Participation in Physical Activity during the School Lunch Break for Girls Aged 12-13 Years

ERIC Educational Resources Information Center

Watson, Amanda; Eliott, Jaklin; Mehta, Kaye

2015-01-01

Given the short-and long-term health implications associated with overweight and obesity plus the likelihood of overweight or obesity to continue into adulthood, addressing the causes of overweight and obesity in childhood is a significant public health concern. One underlying cause of overweight and obesity is insufficient physical activity. The…

Florida Postsecondary Education Security Information Act. Annual Report of Campus Crime Statistics 1991-93 and Annual Assessment of Physical Plant Safety 1994.

ERIC Educational Resources Information Center

Florida State Dept. of Education, Tallahassee. Office of Postsecondary Education Coordination.

This state-mandated report presents crime statistics at higher education institutions in Florida and an assessment of physical plant security. The crime data list numbers of homicides, forcible sex offenses, robberies, aggravated assaults, burglaries/breaking and entering, larcenies and thefts, and motor vehicle thefts for each state university,…

Physical Activity Promotion in Schools: Which Strategies Do Schools (Not) Implement and Which Socioecological Factors Are Associated with Implementation?

ERIC Educational Resources Information Center

Cardon, Greet M.; Van Acker, Ragnar; Seghers, Jan; De Martelaer, Kristine; Haerens, Leen L.; De Bourdeaudhuij, Ilse M. M.

2012-01-01

We studied the implementation and associated factors of strategies (e.g. sports after school and during lunch break, active schoolyards, active school commuting) and organizational principles (e.g. safe bike racks, pupil involvement) that facilitate the physical activity (PA)-promoting role of schools. Key representatives of 111 elementary and 125…

Cosmological constraints on pseudo-Nambu-Goldstone bosons

NASA Technical Reports Server (NTRS)

Frieman, Joshua A.; Jaffe, Andrew H.

1991-01-01

Particle physics models with pseudo-Nambu-Goldstone bosons (PNGBs) are characterized by two mass scales: a global spontaneous symmetry breaking scale, f, and a soft (explicit) symmetry breaking scale, Lambda. General model insensitive constraints were studied on this 2-D parameter space arising from the cosmological and astrophysical effects of PNGBs. In particular, constraints were studied arising from vacuum misalignment and thermal production of PNGBs, topological defects, and the cosmological effects of PNGB decay products, as well as astrophysical constraints from stellar PNGB emission. Bounds on the Peccei-Quinn axion scale, 10(exp 10) GeV approx. = or less than f sub pq approx. = or less than 10(exp 10) to 10(exp 12) GeV, emerge as a special case, where the soft breaking scale is fixed at Lambda sub QCD approx. = 100 MeV.

The importance of sexual health in the elderly: breaking down barriers and taboos.

PubMed

Inelmen, Emine Meral; Sergi, Giuseppe; Girardi, Agostino; Coin, Alessandra; Toffanello, Elena Debora; Cardin, Fabrizio; Manzato, Enzo

2012-06-01

Aging-related physical changes do not necessarily lead to a decline in sexual functioning: good physical and mental health, a positive attitude toward sex in later life, and access to a healthy partner are associated with continued sexual activity, and regular sexual expression is associated with good physical and mental health. However, it is usually assumed that older adults do not have sexual desires, and elderly people often find it difficult to discuss this topic with their doctor. There are many potential barriers concerning sexuality in older age: the lack of a healthy sexual partner, depression, the monotony of a repetitive sexual relationship, a spouse's physical unattractiveness, hormone variability, and illness and/or iatrogenic factors. Adaptive coping strategies can considerably mitigate the impact of such factors, however, and one way of contributing to breaking down barriers and taboos is undoubtedly to ensure that physicians are willing to discuss their patients' sexual history. The aim of this review was to explore the barriers and taboos to sexual expression in seniors, to propose strategies to foster this aspect of their lives, and to help physicians investigate the sexual history of their elderly patients.

Do aggression and rule-breaking have different interpersonal correlates? A study of antisocial behavior subtypes, negative affect, and hostile perceptions of others.

PubMed

Burt, S Alexandra; Mikolajewski, Amy J; Larson, Christine L

2009-01-01

There is mounting evidence that physical aggression and nonaggressive, rule-breaking delinquency constitute two separable though correlated subtypes of antisocial behavior. Even so, it remains unclear whether these behavioral subtypes have meaningfully different interpersonal correlates, particularly as they are subsumed within the same broad domain of antisocial behavior. To evaluate this, we examined whether hostile perceptions of others (assessed via exposure to a series of neutral unknown faces) were linked to level and type of antisocial behavior aggression vs. rule-breaking, and moreover, whether this association persisted even when also considering the common association with negative affect (as manipulated via written recollection of one's best and worst life experiences). Analyses revealed that aggression, but not rule-breaking, was uniquely tied to hostile perceptions of others. Furthermore, this association persisted over and above the common association of both hostile perceptions and aggression with negative affect (at both trait and state levels). Such results provide additional support for clinically meaningful differences between the behavioral subtypes of aggression and nonaggressive rule-breaking and for the independent role of hostile perceptions in aggressive behavior.

Change of Electroweak Nuclear Reaction Rates by CP- and Isospin Symmetry Breaking - A Model Calculation

NASA Astrophysics Data System (ADS)

Stumpf, Harald

2006-09-01

Based on the assumption that electroweak bosons, leptons and quarks possess a substructure of elementary fermionic constituents, in previous papers the effect of CP-symmetry breaking on the effective dynamics of these particles was calculated. Motivated by the phenomenological procedure in this paper, isospin symmetry breaking will be added and the physical consequences of these calculations will be discussed. The dynamical law of the fermionic constituents is given by a relativistically invariant nonlinear spinor field equation with local interaction, canonical quantization, selfregularization and probability interpretation. The corresponding effective dynamics is derived by algebraic weak mapping theorems. In contrast to the commonly applied modifications of the quark mass matrices, CP-symmetry breaking is introduced into this algebraic formalism by an inequivalent vacuum with respect to the CP-invariant case, represented by a modified spinor field propagator. This leads to an extension of the standard model as effective theory which contains besides the "electric" electroweak bosons additional "magnetic" electroweak bosons and corresponding interactions. If furthermore the isospin invariance of the propagator is broken too, it will be demonstrated in detail that in combination with CP-symmetry breaking this induces a considerable modification of electroweak nuclear reaction rates.

Observation of 1-D time dependent non-propagating laser plasma structures using fluid and PIC codes

NASA Astrophysics Data System (ADS)

Verma, Deepa; Bera, Ratan Kumar; Kumar, Atul; Patel, Bhavesh; Das, Amita

2017-12-01

The manuscript reports the observation of time dependent localized and non-propagating structures in the coupled laser plasma system through 1-D fluid and Particle-In-Cell (PIC) simulations. It is reported that such structures form spontaneously as a result of collision amongst certain exact solitonic solutions. They are seen to survive as coherent entities for a long time up to several hundreds of plasma periods. Furthermore, it is shown that such time dependence can also be artificially recreated by significantly disturbing the delicate balance between the radiation and the density fields required for the exact non-propagating solution obtained by Esirkepov et al., JETP 68(1), 36-41 (1998). The ensuing time evolution is an interesting interplay between kinetic and field energies of the system. The electrostatic plasma oscillations are coupled with oscillations in the electromagnetic field. The inhomogeneity of the background and the relativistic nature, however, invariably produces large amplitude density perturbations leading to its wave breaking. In the fluid simulations, the signature of wave breaking can be discerned by a drop in the total energy which evidently gets lost to the grid. The PIC simulations are observed to closely follow the fluid simulations till the point of wave breaking. However, the total energy in the case of PIC simulations is seen to remain conserved throughout the simulations. At the wave breaking, the particles are observed to acquire thermal kinetic energy in the case of PIC. Interestingly, even after wave breaking, compact coherent structures with trapped radiation inside high-density peaks continue to exist both in PIC and fluid simulations. Although the time evolution does not exactly match in the two simulations as it does prior to the process of wave breaking, the time-dependent features exhibited by the remnant structures are characteristically similar.

Key Impact Factors on Dam Break Fatalities

NASA Astrophysics Data System (ADS)

Huang, D.; Yu, Z.; Song, Y.; Han, D.; Li, Y.

2016-12-01

Dam failures can lead to catastrophes on human society. However, there is a lack of research about dam break fatalities, especially on the key factors that affect fatalities. Based on the analysis of historical dam break cases, most studies have used the regression analysis to explore the correlation between those factors and fatalities, but without implementing optimization to find the dominating factors. In order to understand and reduce the risk of fatalities, this study has proposed a new method to select the impact factors on the fatality. It employs an improved ANN (Artificial Neural Network) combined with LOOCV (Leave-one-out cross-validation) and SFS (Stepwise Forward Selection) approach to explore the nonlinear relationship between impact factors and life losses. It not only considers the factors that have been widely used in the literature but also introduces new factors closely involved with fatalities. Dam break cases occurred in China from 1954 to 2013 are summarized, within which twenty-five cases are selected with a comprehensive coverage of geographic position and temporal variation. Twelve impact factors are taken into account as the inputs, i.e., severity of dam break flood (SF), population at risk (PR), public understanding of dam break (UB), warning time (TW), evacuation condition (EC), weather condition during dam break (WB), dam break mode (MB), water storage (SW), building vulnerability (VB), dam break time (TB), average distance from the affected area to the dam (DD) and preventive measures by government (PG).From those, three key factors of SF, MB and TB are chosen. The proposed method is able to extract the key factors, and the derived fatality model performs well in various types of dam break conditions.

Physical and morphological properties of z ~ 3 Lyman break galaxies: dependence on Lyα line emission

NASA Astrophysics Data System (ADS)

Pentericci, L.; Grazian, A.; Scarlata, C.; Fontana, A.; Castellano, M.; Giallongo, E.; Vanzella, E.

2010-05-01

Aims: We investigate the physical and morphological properties of Lyman break galaxies (LBGs) at redshift ~2.5 to ~3.5, to determine if and how they depend on the nature and strength of the Lyα emission. Methods: We selected U-dropout galaxies from the z-detected GOODS-MUSIC catalog by adapting the classical Lyman break criteria on the GOODS filter set. We kept only those galaxies with spectroscopic confirmation, mainly from VIMOS and FORS public observations. Using the full multi-wavelength 14-bands information (U to IRAC), we determined the physical properties of the galaxies through a standard spectral energy distribution fitting procedure with the updated Charlot & Bruzual (2009) templates. We also added other relevant observations of the GOODS field, i.e. the 24 μm observations from Spitzer/MIPS and the 2 MSec Chandra X-ray observations. Finally, using non parametric diagnostics (Gini, Concentration, Asymmetry, M20 and ellipticity), we characterized the rest-frame UV morphologies of the galaxies. We then analyzed how these physical and morphological properties correlate with the presence of the Lyα emission line in the optical spectra. Results: We find that unlike at higher redshift, the dependence of physical properties on the Lyα line is milder: galaxies without Lyα in emission tend to be more massive and dustier than the rest of the sample, but all other parameters, ages, star formation rates (SFR), X-ray emission and UV morphology do not depend strongly on the presence of the Lyα emission. A simple scenario where all LBGs have intrinsically high Lyα emission, but where the dust and neutral hydrogen content (which shapes the final appearance of the Lyα) depend on the mass of the galaxies, is able to reproduce the majority of the observed properties at z˜3. Some modification might be needed to account for the observed evolution of these properties with cosmic epoch, which is also discussed.

Determination of the Proper Rest Time for a Cyclic Mental Task Using ACT-R Architecture.

PubMed

Atashfeshan, Nooshin; Razavi, Hamideh

2017-03-01

Objective Analysis of the effect of mental fatigue on a cognitive task and determination of the right start time for rest breaks in work environments. Background Mental fatigue has been recognized as one of the most important factors influencing individual performance. Subjective and physiological measures are popular methods for analyzing fatigue, but they are restricted to physical experiments. Computational cognitive models are useful for predicting operator performance and can be used for analyzing fatigue in the design phase, particularly in industrial operations and inspections where cognitive tasks are frequent and the effects of mental fatigue are crucial. Method A cyclic mental task is modeled by the ACT-R architecture, and the effect of mental fatigue on response time and error rate is studied. The task includes visual inspections in a production line or control workstation where an operator has to check products' conformity to specifications. Initially, simulated and experimental results are compared using correlation coefficients and paired t test statistics. After validation of the model, the effects are studied by human and simulated results, which are obtained by running 50-minute tests. Results It is revealed that during the last 20 minutes of the tests, the response time increased by 20%, and during the last 12.5 minutes, the error rate increased by 7% on average. Conclusion The proper start time for the rest period can be identified by setting a limit on the error rate or response time. Application The proposed model can be applied early in production planning to decrease the negative effects of mental fatigue by predicting the operator performance. It can also be used for determining the rest breaks in the design phase without an operator in the loop.

a Novel Method for Automation of 3d Hydro Break Line Generation from LIDAR Data Using Matlab

NASA Astrophysics Data System (ADS)

Toscano, G. J.; Gopalam, U.; Devarajan, V.

2013-08-01

Water body detection is necessary to generate hydro break lines, which are in turn useful in creating deliverables such as TINs, contours, DEMs from LiDAR data. Hydro flattening follows the detection and delineation of water bodies (lakes, rivers, ponds, reservoirs, streams etc.) with hydro break lines. Manual hydro break line generation is time consuming and expensive. Accuracy and processing time depend on the number of vertices marked for delineation of break lines. Automation with minimal human intervention is desired for this operation. This paper proposes using a novel histogram analysis of LiDAR elevation data and LiDAR intensity data to automatically detect water bodies. Detection of water bodies using elevation information was verified by checking against LiDAR intensity data since the spectral reflectance of water bodies is very small compared with that of land and vegetation in near infra-red wavelength range. Detection of water bodies using LiDAR intensity data was also verified by checking against LiDAR elevation data. False detections were removed using morphological operations and 3D break lines were generated. Finally, a comparison of automatically generated break lines with their semi-automated/manual counterparts was performed to assess the accuracy of the proposed method and the results were discussed.

Un formalisme de systemes a sauts pour la recirculation optimale des casses dans une machine a papier

NASA Astrophysics Data System (ADS)

Khanbaghi, Maryam

Increasing closure of white water circuits is making mill productivity and quality of paper produced increasingly affected by the occurrence of paper breaks. In this thesis the main objective is the development of white water and broke recirculation policies. The thesis consists of three main parts, respectively corresponding to the synthesis of a statistical model of paper breaks in a paper mill, the basic mathematical setup for the formulation of white water and broke recirculation policies in the mill as a jump linear quadratic regulation problem, and finally the tuning of the control law based on first passage-time theory, and its extension to the case of control sensitive paper break rates. More specifically, in the first part a statistical model of paper machine breaks is developed. We start from the hypothesis that the breaks process is a Markov chain with three states: the first state is the operational one, while the two others are associated with the general types of paper-breaks that can take place in the mill (wet breaks and dry breaks). The Markovian hypothesis is empirically validated. We also establish how paper-break rates are correlated with machine speed and broke recirculation ratio. Subsequently, we show how the obtained Markov chain model of paper-breaks can be used to formulate a machine operating speed parameter optimization problem. In the second part, upon recognizing that paper breaks can be modelled as a Markov chain type of process which, when interacting with the continuous mill dynamics, yields a jump Markov model, jump linear theory is proposed as a means of constructing white water and broke recirculation strategies which minimize process variability. Reduced process variability comes at the expense of relatively large swings in white water and broke tanks level. Since the linear design does not specifically account for constraints on the state-space, under the resulting law, damaging events of tank overflow or emptiness can occur. A heuristic simulation-based approach is proposed to choose the performance measure design parameters to keep the mean time between incidents of fluid in broke and white water tanks either overflowing, or reaching dangerously low levels, sufficiently long. In the third part, a methodology, mainly founded on the first passage-time theory of stochastic processes, is proposed to choose the performance measure design parameters to limit process variability while accounting for the possibility of undesirable tank overflows or tank emptiness. The heart of the approach is an approximation technique for evaluating mean first passage-times of the controlled tanks levels. This technique appears to have an applicability which largely exceeds the problem area it was designed for. Furthermore, the introduction of control sensitive break rates and the analysis of the ensuing control problem are presented. This is to account for the experimentally observed increase in breaks concomitant with flow rate variability.

Increasing children's physical activity levels during recess periods in elementary schools: the effects of providing game equipment.

PubMed

Verstraete, Stefanie J M; Cardon, Greet M; De Clercq, Dirk L R; De Bourdeaudhuij, Ilse M M

2006-08-01

During recess, children can be active on a daily basis, making it an important school environmental factor for the promotion of health-related physical activity. The aim of the present study was to investigate the effects of providing game equipment on children's physical activity levels during morning recess and lunch break in elementary schools. Seven elementary schools were randomly assigned to the intervention group (four schools), including 122 children (75 boys, 47 girls, mean age: 10.8 +/- 0.6 years), and to the control group (three schools), including 113 children (46 boys, 67 girls, mean age: 10.9 +/- 0.7 years). Children's activity levels were measured before and three months after providing game equipment, using MTI accelerometers. During lunch break, children's moderate and vigorous physical activity significantly increased in the intervention group (moderate: from 38 to 50%, vigorous: from 10 to 11%), while it decreased in the control group (moderate: from 44 to 39%, vigorous: from 11 to 5%). At morning recess, providing game equipment was effective in increasing children's moderate physical activity (from 41 to 45%), while it decreased in the control group (from 41 to 34%). Providing game equipment during recess periods was found to be effective in increasing children's physical activity levels. This finding suggests that promoting physical activity through game equipment provision during recess periods can contribute to reach the daily activity levels recommended for good health.

Dependence of Wave-Breaking Statistics on Wind Stress and Wave Development

NASA Technical Reports Server (NTRS)

Katsaros, Kristina B.; Atakturk, Serhad S.

1992-01-01

Incidence of wave breaking for pure wind driven waves has been studied on Lake Washington at wind speeds up to 8 m/s. Video recordings were employed to identify and categorize the breaking events in terms of micro-scale, spilling and plunging breakers. These events were correlated with the magnitude of the wave spectrum measured with a resistance wire wave gauge and band pass filtered between 6 and 10 Hz. An equivalent percentage of breaking crests were found for spilling and plunging events. Wave forcing as measured by wind stress (or friction velocity, u(sub *), squared) and by inverse wave age, u(sub *)/Cp where Cp is the phase velocity of the waves at the peak of the frequency spectrum, were found to be good prerictors of percentage of breaking crests. When combined in a two parameter regression, those two variables gave small standard deviation and had a high correlation coefficient (66 percent). The combination of u(sub *)(exp 2) and u(sub *)/Cp can be understood in physical terms. Furthermore, for the larger values of u(sub *)(exp 2) the dependence of wave braking and wave age was stronger than at the low end of the values u(sub *)(exp 2) and u(sub *)/Cp. Thus, both the level of wave development as determined by inverse wave age, which we may term relative wind effectiveness for wave forcing and the wind forcing on the water surface determine the incidence of wave breaking. Substituting U(sub 10)(sup 3.75) (which is the dependence of whitecap cover found by Monahan and coworkers) an equivalent correlation was found to the prediction by u(sub *)(exp 2). Slightly better standard deviation value and higher correlation coefficient were found by using a Reynolds number as predictor. A two-parameter regression involving u(sub *)(exp 2) and a Reynold's number proposed by Toba and his colleagues which relates u(sub *)(exp 2) and peak wave frequency, improves the correlation even more but is less easy to interpret in physical terms. The equivalent percentage of breaking crests obtained in our previous study was reported at 8.6 percent for a short record obtained at U(sub 10N) of about 6 m/s. Typical values in the current study for similar conditions are 6 percent, which is consistent with the previous study in view of the scatter. In that study we did not have a video recording system, so the observed breaking may include more of the micro-scaic breaking events, and the value, 8.6 percent, is well within the range of highly probable sampling variability.

The Relevance of British Career Break Schemes for American Companies.

ERIC Educational Resources Information Center

Galinsky, Ellen

In recent years, numerous American companies have extended parental leave in order to retain employees and comply with state-imposed mandates. In England, several companies have created the career break, which is a period in which the employee works part-time or takes a complete break from working, typically to raise a family, before resuming his…

78 FR 2711 - Hours of Service of Drivers: U.S. Department of Energy (DOE); Application for Exemption

Federal Register 2010, 2011, 2012, 2013, 2014

2013-01-14

...) for an exemption from the 30-minute rest break provision of the Agency's hours-of-service (HOS... minutes or more of attendance time to meet the HOS rest break requirements providing they do not perform any other work during the break. FMCSA requests public comment on DOE's application for exemption...

Attosecond Light and Science at the Time-scale of the Electron - Coherent X-Rays from Tabletop Ultrafast Lasers

ScienceCinema

Margaret, Murnane [University of Colorado, Boulder and NIST

2017-12-09

Ever since the invention of the laser 50 years ago and its application in nonlinear optics, scientists have been striving to extend coherent laser beams into the x-ray region of the spectrum. Very recently however, the prospects for tabletop coherent sources at very short wavelengths, even in the hard x-ray region of the spectrum at wavelengths < 1nm, have brightened considerably. This advance is possible by taking nonlinear optics techniques to an extreme - physics that is the direct result of a new ability to manipulate electrons on the fastest, attosecond, time-scales of our natural world. Several applications have already been demonstrated, including making a movie of how electrons rearrange in a chemical bond changes shape as a molecule breaks apart, following how fast a magnetic material can flip orientation, understanding how fast heat flows in a nanocircuit, or building a microscope without lenses. Nature 460, 1088 (2009); Science 317, 775 (2007); Physical Review Letters 103, 257402 (2009); Nature Materials 9, 26 (2010); Nature 463, 214 (2010); Science 322, 1207 (2008).

Absence of time-reversal symmetry breaking in the noncentrosymmetric superconductor Mo3Al2C

NASA Astrophysics Data System (ADS)

Bauer, E.; Sekine, C.; Sai, U.; Rogl, P.; Biswas, P. K.; Amato, A.

2014-08-01

Zero-field muon spin rotation and relaxation (μSR) studies carried out on the strongly coupled, noncentrosymmetric superconductor Mo3Al2C,Tc=9 K, did not reveal hints of time-reversal symmetry breaking as was found for a number of other noncentrosymmetric systems. Transverse field measurements performed above and below the superconducting transition temperature defined the temperature dependent London penetration depth, which in turn served to derive from a microscopic point of view a simple s-wave superconducting state in Mo3Al2C. The present investigations also provide fairly solid grounds to conclude that time-reversal symmetry breaking is not an immanent feature of noncentrosymmetric superconductors.

Induction and disappearance of G2 chromatid breaks in lymphocytes after low doses of low-LET gamma-rays and high-LET fast neutrons.

PubMed

Vral, A; Thierens, H; Baeyens, A; De Ridder, L

2002-04-01

To determine by means of the G2 assay the number of chromatid breaks induced by low-LET gamma-rays and high-LET neutrons, and to compare the kinetics of chromatid break rejoining for radiations of different quality. The G2 assay was performed on blood samples of four healthy donors who were irradiated with low-LET gamma-rays and high-LET neutrons. In a first set of experiments a dose-response curve for the formation of chromatid breaks was carried out for gamma-rays and neutrons with doses ranging between 0.1 and 0.5 Gy. In a second set of experiments, the kinetics of chromatid break formation and disappearance were investigated after a dose of 0.5 Gy using post-irradiation times ranging between 0.5 and 3.5 h. For the highest dose of 0.5 Gy, the number of isochromatid breaks was also scored. No significant differences in the number of chromatid breaks were observed between low-LET gamma-rays and high-LET neutrons for the four donors at any of the doses given. The dose-response curves for the formation of chromatid breaks are linear for both radiation qualities and RBEs = 1 were obtained. Scoring of isochromatid breaks at the highest dose of 0.5 Gy revealed that high-LET neutrons were, however, more effective at inducing isochromatid breaks (RBE = 6.2). The rejoining experiments further showed that the kinetics of disappearance of chromatid breaks following irradiation with low-LET gamma-rays or high-LET neutrons were not significantly different. Half-times of 0.92 h for gamma-rays and 0.84 h for neutrons were obtained. Applying the G2 assay, the results demonstrate that at low doses of irradiation, the induction as well as the disappearance of chromatid breaks is independent of the LET of the radiation qualities used (0.24 keV x microm(-1) 60Co gamma-rays and 20 keV x microm(-1) fast neutrons). As these radiation qualities produce the same initial number of double-strand breaks, the results support the signal model that proposes that chromatid breaks are the result of an exchange process which is triggered by a single double-strand break.

Safety of working patterns among UK neuroradiologists: what can we learn from the aviation industry and cognitive science?

PubMed

Reicher, John; Currie, Stuart; Birchall, Daniel

2018-04-01

As the volume and complexity of imaging in the UK continues to rise, there is pressure on radiologists to spend increasing lengths of time reporting to cope with the growing workload. However, there is limited guidance for radiologists about structuring the working day to strike the necessary balance between achieving satisfactory reporting volume and maintaining quality and safety. We surveyed 86 neuroradiologists (receiving 59 responses), regarding time spent reporting, frequency and duration of work breaks, and break activities. Our results demonstrate that some neuroradiologists report for up to 12 h a day and for 4 h before taking a break. Mean duration of breaks is less than 15 min and these often consist of computer screen-based or cognitively demanding tasks. Many areas of medicine have looked to the aviation industry to develop improvements in safety through regulated, standardised practices. There are parallels between the work of air traffic controllers (ATCs) and radiologists. We review the legislation that controls the working hours of UK ATCs to minimise fatigue-related errors, and its scientific basis. We also consider the vigilance decrement, a concept in cognitive science which describes the reduction in performance with increasing time-on-task. We conclude that, in comparison with ATCs, work patterns among radiologists are poorly standardised and potentially dangerous. Evidence suggests that placing limits on reporting time and minimum break duration, as well as ensuring appropriate break activities, can benefit reporting quality. It is imperative that radiologists and managers heed these lessons, to improve standards and protect patients from error.

Theory of self-resonance after inflation. I. Adiabatic and isocurvature Goldstone modes

NASA Astrophysics Data System (ADS)

Hertzberg, Mark P.; Karouby, Johanna; Spitzer, William G.; Becerra, Juana C.; Li, Lanqing

2014-12-01

We develop a theory of self-resonance after inflation. We study a large class of models involving multiple scalar fields with an internal symmetry. For illustration, we often specialize to dimension-four potentials, but we derive results for general potentials. This is the first part of a two part series of papers. Here in Part 1 we especially focus on the behavior of long-wavelength modes, which are found to govern most of the important physics. Since the inflaton background spontaneously breaks the time-translation symmetry and the internal symmetry, we obtain Goldstone modes; these are the adiabatic and isocurvature modes. We find general conditions on the potential for when a large instability band exists for these modes at long wavelengths. For the adiabatic mode, this is determined by a sound speed derived from the time-averaged potential, while for the isocurvature mode, this is determined by a speed derived from a time-averaged auxiliary potential. Interestingly, we find that this instability band usually exists for one of these classes of modes, rather than both simultaneously. We focus on backgrounds that evolve radially in field space, as set up by inflation, and also mention circular orbits, as relevant to Q -balls. In Part 2 [M. P. Hertzberg et al., Phys. Rev. D 90, 123529 (2014)] we derive the central behavior from the underlying description of many-particle quantum mechanics, and introduce a weak breaking of the symmetry to study corrections to particle-antiparticle production from preheating.

Dynamic decision making for dam-break emergency management - Part 2: Application to Tangjiashan landslide dam failure

NASA Astrophysics Data System (ADS)

Peng, M.; Zhang, L. M.

2013-02-01

Tangjiashan landslide dam, which was triggered by the Ms = 8.0 Wenchuan earthquake in 2008 in China, threatened 1.2 million people downstream of the dam. All people in Beichuan Town 3.5 km downstream of the dam and 197 thousand people in Mianyang City 85 km downstream of the dam were evacuated 10 days before the breaching of the dam. Making such an important decision under uncertainty was difficult. This paper applied a dynamic decision-making framework for dam-break emergency management (DYDEM) to help rational decision in the emergency management of the Tangjiashan landslide dam. Three stages are identified with different levels of hydrological, geological and social-economic information along the timeline of the landslide dam failure event. The probability of dam failure is taken as a time series. The dam breaching parameters are predicted with a set of empirical models in stage 1 when no soil property information is known, and a physical model in stages 2 and 3 when knowledge of soil properties has been obtained. The flood routing downstream of the dam in these three stages is analyzed to evaluate the population at risk (PAR). The flood consequences, including evacuation costs, flood damage and monetized loss of life, are evaluated as functions of warning time using a human risk analysis model based on Bayesian networks. Finally, dynamic decision analysis is conducted to find the optimal time to evacuate the population at risk with minimum total loss in each of these three stages.

The Correlation of Interphase Chromatin Structure with the Radiation-Induced Inter- and Intrachromosome Exchange Hotspots

NASA Technical Reports Server (NTRS)

Zhang, Ye; Mangala, Lingegowda S.; Purgason, Ashley M.; Hada, Megumi; Cucinotta, Francis A.; Wu, Honglu

2011-01-01

To investigate the relationship between chromosome aberrations induced by radiation and chromatin folding, we reconstructed three dimensional structure of chromosome 3 and measured the physical distances between different regions of the chromosome. Previously, we have investigated the location of breaks involved in inter- and intrachromosomal type exchange events in human chromosome 3, using the multicolor banding in situ hybridization (mBAND) technique. In human epithelial cells exposed to both low- and high-LET radiations in vitro, we reported that intra-chromosome exchanges occurred preferentially between a break in the 3p21 and one in the 3q11 regions, and the breaks involving in inter-chromosome exchanges occurred in two regions towards the telomeres of the chromosome. Exchanges were also observed between a break in 3p21 and one in 3q26, but few exchanges were observed between breaks in 3q11 and 3q26, even though the two regions are located on the same arm of the chromosome. In this study, human epithelial cells were fixed at G1 phase and the interphase cells were hybridized using the XCyte3 mBAND kit from MetaSystems. The z-section images of chromosome 3 were captured with a Leica and an LSM 510 Meta laser scanning confocal microscopes. A total of 100 chromosomes were analyzed. The reconstruction of three dimensional structure of interphase chromosome 3 with six different colored regions was achieved using the Imaris software. The relative distance between different regions was measured as well. We further analyzed fragile sites on the chromosome that have been identified in various types of cancers. The data showed that, in majority of the cells, the regions containing 3p21 and 3q11 are colocalized in the center of the chromosome, whereas, the regions towards the telomeres of the chromosome are either physically wrapping outside the chromosome center or with arms sticking out. Our results demonstrated that the distribution of breaks involved in radiation-induced inter and intra-chromosome aberrations depends upon both the location of fragile sites and the folding of chromatins.

PT-symmetry breaking with divergent potentials: Lattice and continuum cases

NASA Astrophysics Data System (ADS)

Joglekar, Yogesh N.; Scott, Derek D.; Saxena, Avadh

2014-09-01

We investigate the parity- and time-reversal (PT-) symmetry breaking in lattice models in the presence of long-ranged, non-Hermitian, PT-symmetric potentials that remain finite or become divergent in the continuum limit. By scaling analysis of the fragile PT threshold for an open finite lattice, we show that continuum loss-gain potentials Vα(x)∝i|x|αsgn(x) have a positive PT-breaking threshold for α >-2, and a zero threshold for α ≤-2. When α <0 localized states with complex (conjugate) energies in the continuum energy band occur at higher loss-gain strengths. We investigate the signatures of PT-symmetry breaking in coupled waveguides, and show that the emergence of localized states dramatically shortens the relevant time scale in the PT-symmetry broken region.

The school environment and adolescent physical activity and sedentary behaviour: a mixed‐studies systematic review

PubMed Central

Atkin, A. J.; Corder, K.; Suhrcke, M.; van Sluijs, E. M. F.

2015-01-01

Summary There is increasing academic and policy interest in interventions aiming to promote young people's health by ensuring that the school environment supports healthy behaviours. The purpose of this review was to summarize the current evidence on school‐based policy, physical and social‐environmental influences on adolescent physical activity and sedentary behaviour. Electronic databases were searched to identify studies that (1) involved healthy adolescents (11–18 years old), (2) investigated school‐environmental influences and (3) reported a physical activity and/or sedentary behaviour outcome or theme. Findings were synthesized using a non‐quantitative synthesis and thematic analysis. Ninety‐three papers of mixed methodological quality were included. A range of school‐based policy (e.g. break time length), physical (e.g. facilities) and social‐environmental (e.g. teacher behaviours) factors were associated with adolescent physical activity, with limited research on sedentary behaviour. The mixed‐studies synthesis revealed the importance of specific activity settings (type and location) and intramural sport opportunities for all students. Important physical education‐related factors were a mastery‐oriented motivational climate and autonomy supportive teaching behaviours. Qualitative evidence highlighted the influence of the wider school climate and shed light on complexities of the associations observed in the quantitative literature. This review identifies future research needs and discusses potential intervention approaches to be considered. PMID:26680609

The school environment and adolescent physical activity and sedentary behaviour: a mixed-studies systematic review.

PubMed

Morton, K L; Atkin, A J; Corder, K; Suhrcke, M; van Sluijs, E M F

2016-02-01

There is increasing academic and policy interest in interventions aiming to promote young people's health by ensuring that the school environment supports healthy behaviours. The purpose of this review was to summarize the current evidence on school-based policy, physical and social-environmental influences on adolescent physical activity and sedentary behaviour. Electronic databases were searched to identify studies that (1) involved healthy adolescents (11-18 years old), (2) investigated school-environmental influences and (3) reported a physical activity and/or sedentary behaviour outcome or theme. Findings were synthesized using a non-quantitative synthesis and thematic analysis. Ninety-three papers of mixed methodological quality were included. A range of school-based policy (e.g. break time length), physical (e.g. facilities) and social-environmental (e.g. teacher behaviours) factors were associated with adolescent physical activity, with limited research on sedentary behaviour. The mixed-studies synthesis revealed the importance of specific activity settings (type and location) and intramural sport opportunities for all students. Important physical education-related factors were a mastery-oriented motivational climate and autonomy supportive teaching behaviours. Qualitative evidence highlighted the influence of the wider school climate and shed light on complexities of the associations observed in the quantitative literature. This review identifies future research needs and discusses potential intervention approaches to be considered. © 2015 World Obesity.

PREFACE: Prospects in Neutrino Physics 2013 - NuPhys2013

NASA Astrophysics Data System (ADS)

2015-04-01

The first "Prospects in Neutrino Physics 2013 - NuPhys2013" conference was held at the Institute of Physics, IoP, London, 19-20 December 2013 and was attended by about 130 delegates from institutions worldwide. Lunch and coffee breaks allowed discussions among delegates and speakers to take place in an informal setting. This conference is unique in discussing the worldwide strategy to address unresolved issues in neutrino physics, and shape the future directions of particle physics. We discussed the current status and focussed especially on the prospects of future experiments, their performance and physics reach. It is particularly timely due to the recent measurements in neutrino physics and planned worldwide experiments. The following topics were addressed: • Theory and Phenomenology Perspectives • Future Long and Short Baseline Neutrino Oscillation Experiments • Reactor neutrino and flux • Neutrinoless double beta decays • Solar, atmospheric, supernova neutrinos • Neutrino cosmology in which both the phenomenological and experimental aspects were equally addressed. World-leading experts in the different neutrino areas were invited to give review talks. To encourage and facilitate the participation of early-career researchers and PhD students, a poster session formed a key aspect of this meeting. The conference was organized by Francesca Di Lodovico and Silvia Pascoli. It was sponsored by the IoP through their Topic Research Meeting Grant, and also supported by Durham IPPP, ERC-207282, FP7 invisibles project, Queen Mary University of London.

[Changes in the forms of industrial production and their effects on workers' health].

PubMed

Fernandes, Rita de Cássia Pereira; Assunção, Ada Avila; Carvalho, Fernando Martins

2010-06-01

This study aimed to identify determinants of health in workers of plastic industries. Production organization, machinery from maintenance and productive areas, and workers' characteristics of 14 plastic industries from Greater Salvador, Bahia State, Brazil, were described. Data were collected about development policy of each company; marketing, operational procedures; production and quality requirements, and formal rules of work organization. High strain management techniques for production time reduction have been implemented. The increase of work rhythm, reduction of break time, and a situation of high cognitive demand impose to workers anomalous body positioning for performing tasks that imply repetitive movements. Physical and psychosocial demands (repetitive work, lower control of the worker on his own tasks, time pressure and job dissatisfaction) compose a complex of conditions adverse to workers' health. Changes in production management, personnel and business impose new strains into the development of task by the workers and bringing in new risk factors to workers' health.

Maximal Rashba-like spin splitting via kinetic-energy-coupled inversion-symmetry breaking.

PubMed

Sunko, Veronika; Rosner, H; Kushwaha, P; Khim, S; Mazzola, F; Bawden, L; Clark, O J; Riley, J M; Kasinathan, D; Haverkort, M W; Kim, T K; Hoesch, M; Fujii, J; Vobornik, I; Mackenzie, A P; King, P D C

2017-09-27

Engineering and enhancing the breaking of inversion symmetry in solids-that is, allowing electrons to differentiate between 'up' and 'down'-is a key goal in condensed-matter physics and materials science because it can be used to stabilize states that are of fundamental interest and also have potential practical applications. Examples include improved ferroelectrics for memory devices and materials that host Majorana zero modes for quantum computing. Although inversion symmetry is naturally broken in several crystalline environments, such as at surfaces and interfaces, maximizing the influence of this effect on the electronic states of interest remains a challenge. Here we present a mechanism for realizing a much larger coupling of inversion-symmetry breaking to itinerant surface electrons than is typically achieved. The key element is a pronounced asymmetry of surface hopping energies-that is, a kinetic-energy-coupled inversion-symmetry breaking, the energy scale of which is a substantial fraction of the bandwidth. Using spin- and angle-resolved photoemission spectroscopy, we demonstrate that such a strong inversion-symmetry breaking, when combined with spin-orbit interactions, can mediate Rashba-like spin splittings that are much larger than would typically be expected. The energy scale of the inversion-symmetry breaking that we achieve is so large that the spin splitting in the CoO 2 - and RhO 2 -derived surface states of delafossite oxides becomes controlled by the full atomic spin-orbit coupling of the 3d and 4d transition metals, resulting in some of the largest known Rashba-like spin splittings. The core structural building blocks that facilitate the bandwidth-scaled inversion-symmetry breaking are common to numerous materials. Our findings therefore provide opportunities for creating spin-textured states and suggest routes to interfacial control of inversion-symmetry breaking in designer heterostructures of oxides and other material classes.

On the upper ocean turbulent dissipation rate due to microscale breakers and small whitecaps

NASA Astrophysics Data System (ADS)

Banner, Michael L.; Morison, Russel P.

2018-06-01

In ocean wave modelling, accurately computing the evolution of the wind-wave spectrum depends on the source terms and the spectral bandwidth used. The wave dissipation rate source term which spectrally quantifies wave breaking and other dissipative processes remains poorly understood, including the spectral bandwidth needed to capture the essential model physics. The observational study of Sutherland and Melville (2015a) investigated the relative dissipation rate contributions of breaking waves, from large-scale whitecaps to microbreakers. They concluded that a large fraction of wave energy was dissipated by microbreakers. However, in strong contrast with their findings, our analysis of their data and other recent data sets shows that for young seas, microbreakers and small whitecaps contribute only a small fraction of the total breaking wave dissipation rate. For older seas, we find microbreakers and small whitecaps contribute a large fraction of the breaking wave dissipation rate, but this is only a small fraction of the total dissipation rate, which is now dominated by non-breaking contributions. Hence, for all the wave age conditions observed, microbreakers make an insignificant contribution to the total wave dissipation rate in the wave boundary layer. We tested the sensitivity of the results to the SM15a whitecap analysis methodology by transforming the SM15a breaking data using our breaking crest processing methodology. This resulted in the small-scale breaking waves making an even smaller contribution to the total wave dissipation rate, and so the result is independent of the breaker processing methodology. Comparison with other near-surface total TKE dissipation rate observations also support this conclusion. These contributions to the spectral dissipation rate in ocean wave models are small and need not be explicitly resolved.

Break in Sedentary Behavior Reduces the Risk of Noncommunicable Diseases and Cardiometabolic Risk Factors among Workers in a Petroleum Company

PubMed Central

Jalayondeja, Chutima; Jalayondeja, Wattana; Mekhora, Keerin; Bhuanantanondh, Petcharatana; Dusadi-Isariyavong, Asadang; Upiriyasakul, Rujiret

2017-01-01

Although prolonged sitting appears as a novel risk factor related to health outcomes for all ages, its association needs to be replicated in occupational conditions. This study explored the associations between sedentary behavior and four noncommunicable diseases (NCDs) as well as two cardiometabolic risk factors (CMRFs) among workers in a petroleum company, Thailand. All workers were invited to complete the online self-report questionnaire. Sedentary behavior was measured as the amount of time sitting at work, during recreation, and while commuting. Out of 3365 workers contacted, 1133 (34%) participated. Prevalence of NCDs and CMRFs was 36% and was positively associated with sedentary behavior. After adjusting for age, BMI, and exercise, the risk of NCDs and CMRFs for sedentary office work was 40% greater compared with more active field work. Those who took a break without sitting more than twice a day and commuted by walking or cycling had less risk of NCDs and CMRFs. The total duration of sedentary behavior was 10 h/day, and two-thirds of that total was workplace sitting. This was significantly associated with NCDs and CMRFs (p < 0.001). Day-and-night rotating shiftwork was negatively associated with NCDs and CMRFs (p < 0.001). Sedentary behavior should be considered a health risk among workers. Hence, to promote a healthy lifestyle and safe workplace, organizations should encourage standing activities during break and physically active commutes, and have workers avoid prolonged sitting. PMID:28486414

Break in Sedentary Behavior Reduces the Risk of Noncommunicable Diseases and Cardiometabolic Risk Factors among Workers in a Petroleum Company.

PubMed

Jalayondeja, Chutima; Jalayondeja, Wattana; Mekhora, Keerin; Bhuanantanondh, Petcharatana; Dusadi-Isariyavong, Asadang; Upiriyasakul, Rujiret

2017-05-09

Although prolonged sitting appears as a novel risk factor related to health outcomes for all ages, its association needs to be replicated in occupational conditions. This study explored the associations between sedentary behavior and four noncommunicable diseases (NCDs) as well as two cardiometabolic risk factors (CMRFs) among workers in a petroleum company, Thailand. All workers were invited to complete the online self-report questionnaire. Sedentary behavior was measured as the amount of time sitting at work, during recreation, and while commuting. Out of 3365 workers contacted, 1133 (34%) participated. Prevalence of NCDs and CMRFs was 36% and was positively associated with sedentary behavior. After adjusting for age, BMI, and exercise, the risk of NCDs and CMRFs for sedentary office work was 40% greater compared with more active field work. Those who took a break without sitting more than twice a day and commuted by walking or cycling had less risk of NCDs and CMRFs. The total duration of sedentary behavior was 10 h/day, and two-thirds of that total was workplace sitting. This was significantly associated with NCDs and CMRFs ( p < 0.001). Day-and-night rotating shiftwork was negatively associated with NCDs and CMRFs ( p < 0.001). Sedentary behavior should be considered a health risk among workers. Hence, to promote a healthy lifestyle and safe workplace, organizations should encourage standing activities during break and physically active commutes, and have workers avoid prolonged sitting.

Monitoring the degradation of physical properties and fire hazards of high-impact polystyrene composite with different ageing time in natural environments.

PubMed

Wang, Bibo; Zhang, Yan; Tao, Youji; Zhou, Xia; Song, Lei; Jie, Ganxin; Hu, Yuan

2018-06-15

The current study aims at monitoring the role of the different natural environments on the physical properties and fire hazards of HIPS composites ageing in Turpan and Qionghai. The results indicated that the chromatic aberration and degradation of surface appearance intensified with the increasing ageing time. More flame retardants migrated and were eroded for HIPS composites ageing in Qionghai than those ageing in Turpan, which was caused by the combination of sunlight, high temperature and rainwater in Qionghai. After degradation in the natural environments, the HIPS composites possessed the lower thermal stability and char residues, more toxic gases release, higher peak heat release rate and fire hazard. For example, the peak heat release rate in Qionghai increased by 88.9%, which is much higher than that of in Turpan (55.6%). Moreover, the tensile strength and elongation at break decreased by 46% and 59% for HIPS composites ageing in Turpan and reduced by 53% and 67% for HIPS composites aged in Qionghai, respectively. The results demonstrate that more serious degradation of physical properties and higher fire hazard for HIPS composites ageing in Qionghai than those in Turpan due to the different natural ageing environments. Copyright © 2018 Elsevier B.V. All rights reserved.

42 CFR 136.23 - Persons to whom contract health services will be provided.

Code of Federal Regulations, 2011 CFR

2011-10-01

...—during their full-time attendance at programs of vocational, technical, or academic education, including normal school breaks (such as vacations, semester or other scheduled breaks occurring during their... who were eligible for contract health services at the time of the court order shall continue to be...

26 CFR 1.410(a)-7 - Elapsed time.

Code of Federal Regulations, 2011 CFR

2011-04-01

... period of severance from service in order to determine a “break in service” (see paragraph (a)(3)(v) of... employers maintaining the plan. The purpose of the period of severance is to apply the statutory “break in... plan using the elapsed time method of crediting service for one or more classifications of employees...

26 CFR 1.410(a)-7 - Elapsed time.

Code of Federal Regulations, 2012 CFR

2012-04-01

... period of severance from service in order to determine a “break in service” (see paragraph (a)(3)(v) of... employers maintaining the plan. The purpose of the period of severance is to apply the statutory “break in... plan using the elapsed time method of crediting service for one or more classifications of employees...

Is More Area-Level Crime Associated With More Sitting and Less Physical Activity? Longitudinal Evidence From 37,162 Australians

PubMed Central

Astell-Burt, Thomas; Feng, Xiaoqi; Kolt, Gregory S.; Jalaludin, Bin

2016-01-01

Does a rise in crime result in increased sitting time and a reduction in physical activity? We used unobserved (“fixed”)-effects models to examine associations between change in objectively measured crime (nondomestic violence, malicious damage, breaking and entering, and stealing, theft, and robbery) in Australia and measures of sitting time, walking, and moderate-to-vigorous physical activity (MVPA) in a residentially stable sample of 17,474 men and 19,688 women at baseline (2006–2008) and follow-up (2009–2010). Possible sources of time-varying confounding included age, income, economic status, relationship (couple) status, and physical functioning. In adjusted models, an increase in all crimes of 10 counts per 1,000 residents was associated with an increase in sitting time (hours/day) among men (β = 0.21, 95% confidence interval (CI): 0.17, 0.25) and women (β = 0.18, 95% CI: 0.15, 0.22). Counterintuitively, the same increase in crime was also associated with an increase in the weekly number of ≥10-minute walking sessions (men: rate ratio (RR) = 1.01 (95% CI: 1.01, 1.02); women: RR = 1.00 (95% CI: 0.99, 1.01)) and MVPA sessions (men: RR = 1.02 (95% CI: 1.02, 1.03); women: RR = 1.01 (95% CI: 1.00, 1.02)). Similar associations were found for the other area-level crime indicators. While area-level crime prevention may be considered a lever for promoting more active lifestyles, these results suggest that the association is not unequivocal. PMID:27856450

Is More Area-Level Crime Associated With More Sitting and Less Physical Activity? Longitudinal Evidence From 37,162 Australians.

PubMed

Astell-Burt, Thomas; Feng, Xiaoqi; Kolt, Gregory S; Jalaludin, Bin

2016-12-15

Does a rise in crime result in increased sitting time and a reduction in physical activity? We used unobserved ("fixed")-effects models to examine associations between change in objectively measured crime (nondomestic violence, malicious damage, breaking and entering, and stealing, theft, and robbery) in Australia and measures of sitting time, walking, and moderate-to-vigorous physical activity (MVPA) in a residentially stable sample of 17,474 men and 19,688 women at baseline (2006-2008) and follow-up (2009-2010). Possible sources of time-varying confounding included age, income, economic status, relationship (couple) status, and physical functioning. In adjusted models, an increase in all crimes of 10 counts per 1,000 residents was associated with an increase in sitting time (hours/day) among men (β = 0.21, 95% confidence interval (CI): 0.17, 0.25) and women (β = 0.18, 95% CI: 0.15, 0.22). Counterintuitively, the same increase in crime was also associated with an increase in the weekly number of ≥10-minute walking sessions (men: rate ratio (RR) = 1.01 (95% CI: 1.01, 1.02); women: RR = 1.00 (95% CI: 0.99, 1.01)) and MVPA sessions (men: RR = 1.02 (95% CI: 1.02, 1.03); women: RR = 1.01 (95% CI: 1.00, 1.02)). Similar associations were found for the other area-level crime indicators. While area-level crime prevention may be considered a lever for promoting more active lifestyles, these results suggest that the association is not unequivocal. © The Author 2016. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health.

Emergent Phenomena at Oxide Interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, H.Y.

2012-02-16

Transition metal oxides (TMOs) are an ideal arena for the study of electronic correlations because the s-electrons of the transition metal ions are removed and transferred to oxygen ions, and hence the strongly correlated d-electrons determine their physical properties such as electrical transport, magnetism, optical response, thermal conductivity, and superconductivity. These electron correlations prohibit the double occupancy of metal sites and induce a local entanglement of charge, spin, and orbital degrees of freedom. This gives rise to a variety of phenomena, e.g., Mott insulators, various charge/spin/orbital orderings, metal-insulator transitions, multiferroics, and superconductivity. In recent years, there has been a burstmore » of activity to manipulate these phenomena, as well as create new ones, using oxide heterostructures. Most fundamental to understanding the physical properties of TMOs is the concept of symmetry of the order parameter. As Landau recognized, the essence of phase transitions is the change of the symmetry. For example, ferromagnetic ordering breaks the rotational symmetry in spin space, i.e., the ordered phase has lower symmetry than the Hamiltonian of the system. There are three most important symmetries to be considered here. (i) Spatial inversion (I), defined as r {yields} -r. In the case of an insulator, breaking this symmetry can lead to spontaneous electric polarization, i.e. ferroelectricity, or pyroelectricity once the point group belongs to polar group symmetry. (ii) Time-reversal symmetry (T) defined as t {yields} -t. In quantum mechanics, the time-evolution of the wave-function {Psi} is given by the phase factor e{sup -iEt/{h_bar}} with E being the energy, and hence time-reversal basically corresponds to taking the complex conjugate of the wave-function. Also the spin, which is induced by the 'spinning' of the particle, is reversed by time-reversal. Broken T-symmetry is most naturally associated with magnetism, since the spin operator changes sign with T-operation. (iii) Gauge symmetry (G), which is associated with a change in the phase of the wave-function as {Psi} {yields} e{sup i{theta}}{Psi}. Gauge symmetry is connected to the law of charge conservation, and broken G-symmetry corresponds to superconductivity/superfluidity. To summarize, the interplay among these electronic degrees of freedom produces various forms of symmetry breaking patterns of I, T, and G, leading to novel emergent phenomena, which can appear only by the collective behavior of electrons and cannot be expected from individual electrons. Figure 1 shows this schematically by means of several representative phenomena. From this viewpoint, the interfaces of TMOs offer a unique and important laboratory because I is already broken by the structure itself, and the detailed form of broken I-symmetry can often be designed. Also, two-dimensionality usually enhances the effects of electron correlations by reducing their kinetic energy. These two features of oxide interfaces produce many novel effects and functions that cannot be attained in bulk form. Given that the electromagnetic responses are a major source of the physical properties of solids, and new gauge structures often appear in correlated electronic systems, we put 'emergent electromagnetism' at the center of Fig. 1.« less

Propagation and Breaking at High Altitudes of Gravity Waves Excited by Tropospheric Forcing

NASA Technical Reports Server (NTRS)

Prusa, Joseph M.; Smolarkiewicz, Piotr K.; Garcia, Rolando R.

1996-01-01

An anelastic approximation is used with a time-variable coordinate transformation to formulate a two-dimensional numerical model that describes the evolution of gravity waves. The model is solved using a semi-Lagrangian method with monotone (nonoscillatory) interpolation of all advected fields. The time-variable transformation is used to generate disturbances at the lower boundary that approximate the effect of a traveling line of thunderstorms (a squall line) or of flow over a broad topographic obstacle. The vertical propagation and breaking of the gravity wave field (under conditions typical of summer solstice) is illustrated for each of these cases. It is shown that the wave field at high altitudes is dominated by a single horizontal wavelength; which is not always related simply to the horizontal dimension of the source. The morphology of wave breaking depends on the horizontal wavelength; for sufficiently short waves, breaking involves roughly one half of the wavelength. In common with other studies, it is found that the breaking waves undergo "self-acceleration," such that the zonal-mean intrinsic frequency remains approximately constant in spite of large changes in the background wind. It is also shown that many of the features obtained in the calculations can be understood in terms of linear wave theory. In particular, linear theory provides insights into the wavelength of the waves that break at high altitudes, the onset and evolution of breaking. the horizontal extent of the breaking region and its position relative to the forcing, and the minimum and maximum altitudes where breaking occurs. Wave breaking ceases at the altitude where the background dissipation rate (which in our model is a proxy for molecular diffusion) becomes greater than the rate of dissipation due to wave breaking, This altitude, in effect, the model turbopause, is shown to depend on a relatively small number of parameters that characterize the waves and the background state.

Discrete symmetries with neutral mesons

NASA Astrophysics Data System (ADS)

Bernabéu, José

2018-01-01

Symmetries, and Symmetry Breakings, in the Laws of Physics play a crucial role in Fundamental Science. Parity and Charge Conjugation Violations prompted the consideration of Chiral Fields in the construction of the Standard Model, whereas CP-Violation needed at least three families of Quarks leading to Flavour Physics. In this Lecture I discuss the Conceptual Basis and the present experimental results for a Direct Evidence of Separate Reversal-in-Time T, CP and CPT Genuine Asymmetries in Decaying Particles like Neutral Meson Transitions, using Quantum Entanglement and the Decay as a Filtering Measurement. The eight transitions associated to the Flavour-CP eigenstate decay products of entangled neutral mesons have demonstrated with impressive significance a separate evidence of TRV and CPV in Bd-physics, whereas a CPTV asymmetry shows a 2σ effect interpreted as an upper limit. Novel CPTV observables are discussed for K physics at KLOE-2, including the difference between the semileptonic asymmetries from KL and KS, the ratios of double decay rate Intensities to Flavour-CP eigenstate decay products and the ω-effect. Their observation would lead to a change of paradigm beyond Quantum Field Theory, however there is nothing in Quantum Mechanics forbidding CPTV.

Cognitive Load Theory and the Use of Worked Examples as an Instructional Strategy in Physics for Distance Learners: A Preliminary Study

ERIC Educational Resources Information Center

Saw, Kim Guan

2017-01-01

This article revisits the cognitive load theory to explore the use of worked examples to teach a selected topic in a higher level undergraduate physics course for distance learners at the School of Distance Education, Universiti Sains Malaysia. With a break of several years from receiving formal education and having only minimum science…

Sticks and Stones May Break My Bones, but Names will Make Me Feel Sick: The Psychosocial, Somatic, and Scholastic Consequences of Peer Harassment

ERIC Educational Resources Information Center

Nishina, Adrienne; Juvonen, Jaana; Witkow, Melissa R.

2005-01-01

This study examined associations among peer victimization, psychosocial problems, physical symptoms, and school functioning across the 1st year in middle school. An ethnically diverse sample of urban 6th graders (N = 1,526) reported on their perceptions of peer victimization, psychosocial adjustment, and physical symptoms during fall and spring.…

Breaking down the Barriers: Insights into Using a Student Centred Games Approach in Australian and Malaysian Pre-Service Settings

ERIC Educational Resources Information Center

Peters, Jacqui; Shuck, Lisa

2009-01-01

Teacher education in physical education has received much attention in literature over the years. Vying for our attention as teacher educators in physical education are a range of pedagogical models. Teaching Games for Understanding (TGfU) is one such model. This autoethnographical account explores our teaching of TGfU in two culturally diverse…

Breaking Down Gender Stereotypes: Increasing 5th Grade Physical Education Participation by Building Self Esteem

ERIC Educational Resources Information Center

Jeffries, Cindy A.

2009-01-01

It has become apparent that in recent years the issue of childhood obesity is becoming the number one health risk among children in the United States. Making sure that children participate in daily physical education class is one way to combat the obesity epidemic. The purpose of this action research project was to improve the active participation…

Remote sensing signatures of oceanic whitecap at different wavelengths

NASA Astrophysics Data System (ADS)

Anguelova, M. D.; Dowgiallo, D. J.; Smith, G. B.; Means, S. L.; Savelyev, I.; Frick, G. M.; Snow, C. M.; Schindall, J. A.; Bobak, J. P.

2012-12-01

Oceanic whitecaps are the most direct surface expression of breaking wind waves in the ocean. Whitecap fraction quantifies the breaking events and is thus a suitable forcing variable for parameterizing and predicting various air-sea interaction processes. To this end, we have compiled a database of whitecap fraction W from satellites-borne microwave radiometric observations. These observations provide the total W including foam generated during active breaking of wind-driven waves and residual foam left behind by these breaking waves. However, the whitecap fraction associated with the actively breaking waves WA is needed for dynamic air-sea processes in the upper ocean such as turbulent mixing, gas exchange, ocean ambient noise, and spray-mediated intensification of tropical storms. To parameterize such processes, a database of WA separate from W is needed. We pursue this separation of WA from W by combining the Phillips concept of breaking wave statistics which connects WA with the energy dissipation rate of breaking waves and parametric estimates of energy dissipation from wave spectra measured from buoys. We seek additional physical understanding of, and experimental support for, this separation with a multi-instrumental field campaign. The instrumentation deployed includes a suite of sensors recording the whitecaps and breaking waves on the surface over wide range of the electromagnetic spectrum: visible (video cameras), infrared (IR camera), and microwave (radiometers at two frequencies, 10 GHz and 37 GHz). An acoustic array with three nested-aperture array at frequencies up to 2.4 kHz and aerosol/particle counter provide data for the bubbles generated beneath and sea spray produced above the whitecaps. We also deployed a transmitter horn to collect data useful to asses Radio Frequency Interference (RFI), which affects the collection and accuracy of satellite-based data. Various auxiliary data such as wind speed, air temperature, humidity, wave field, and water temperature profile characterize the experimental conditions. The goal of this field campaign is to provide experimental data for determining WA and W independently from the Phillips concept for energy dissipation. In these measurements, we rely on the good separation between WA and W in the IR region of the electromagnetic spectrum. We use the IR data to identify a separation criterion which then can be applied to time series of microwave and acoustic data. Obtaining WA via this separation criterion and comparing the results with those from the Phillips concept, we will have additional possibility to constrain WA obtained using energy dissipation. The measurements are made in April-May, 2012, on the Floating Instrument Platform (FLIP) drifting along the coast of California from Monterey Bay south toward Point Conception. We describe the experiment, characterize the study site, and present first data collected during this campaign.

NSTX-U Advances in Real-Time C++11 on Linux

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erickson, Keith G.

Programming languages like C and Ada combined with proprietary embedded operating systems have dominated the real-time application space for decades. The new C++11standard includes native, language-level support for concurrency, a required feature for any nontrivial event-oriented real-time software. Threads, Locks, and Atomics now exist to provide the necessary tools to build the structures that make up the foundation of a complex real-time system. The National Spherical Torus Experiment Upgrade (NSTX-U) at the Princeton Plasma Physics Laboratory (PPPL) is breaking new ground with the language as applied to the needs of fusion devices. A new Digital Coil Protection System (DCPS) willmore » serve as the main protection mechanism for the magnetic coils, and it is written entirely in C++11 running on Concurrent Computer Corporation's real-time operating system, RedHawk Linux. It runs over 600 algorithms in a 5 kHz control loop that determine whether or not to shut down operations before physical damage occurs. To accomplish this, NSTX-U engineers developed software tools that do not currently exist elsewhere, including real-time atomic synchronization, real-time containers, and a real-time logging framework. Together with a recent (and carefully configured) version of the GCC compiler, these tools enable data acquisition, processing, and output using a conventional operating system to meet a hard real-time deadline (that is, missing one periodic is a failure) of 200 microseconds.« less

NSTX-U Advances in Real-Time C++11 on Linux

DOE PAGES

Erickson, Keith G.

2015-08-14

Programming languages like C and Ada combined with proprietary embedded operating systems have dominated the real-time application space for decades. The new C++11standard includes native, language-level support for concurrency, a required feature for any nontrivial event-oriented real-time software. Threads, Locks, and Atomics now exist to provide the necessary tools to build the structures that make up the foundation of a complex real-time system. The National Spherical Torus Experiment Upgrade (NSTX-U) at the Princeton Plasma Physics Laboratory (PPPL) is breaking new ground with the language as applied to the needs of fusion devices. A new Digital Coil Protection System (DCPS) willmore » serve as the main protection mechanism for the magnetic coils, and it is written entirely in C++11 running on Concurrent Computer Corporation's real-time operating system, RedHawk Linux. It runs over 600 algorithms in a 5 kHz control loop that determine whether or not to shut down operations before physical damage occurs. To accomplish this, NSTX-U engineers developed software tools that do not currently exist elsewhere, including real-time atomic synchronization, real-time containers, and a real-time logging framework. Together with a recent (and carefully configured) version of the GCC compiler, these tools enable data acquisition, processing, and output using a conventional operating system to meet a hard real-time deadline (that is, missing one periodic is a failure) of 200 microseconds.« less

Posture Allocation Revisited: Breaking the Sedentary Threshold of Energy Expenditure for Obesity Management

PubMed Central

Miles-Chan, Jennifer L.; Dulloo, Abdul G.

2017-01-01

There is increasing recognition that low-intensity physical activities of daily life play an important role in achieving energy balance and that their societal erosion through substitution with sedentary (mostly sitting) behaviors, whether occupational or for leisure, impact importantly on the obesity epidemic. This has generated considerable interest for better monitoring, characterizing, and promoting countermeasures to sedentariness through a plethora of low-level physical activities (e.g., active workstations, standing desks, sitting breaks), amid the contention that altering posture allocation (lying, sitting, standing) can modify energy expenditure to impact upon body weight regulation and health. In addressing this contention, this paper first revisits the past and more recent literature on postural energetics, with particular emphasis on potential determinants of the large inter-individual variability in the energy cost of standing and the impact of posture on fat oxidation. It subsequently analyses the available data pertaining to various strategies by which posture allocations, coupled with light physical activity, may increase energy expenditure beyond the sedentary threshold, and their relevance as potential targets for obesity management. PMID:28690547

78 FR 32700 - Hours of Service of Drivers: U.S. Department of Energy (DOE); Application for Exemption

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-31

...) an exemption from the minimum 30-minute rest break provision of the Agency's hours-of-service (HOS... minutes or more of ``attendance time'' to meet the HOS rest break requirements providing they do not perform any other work during the break. DATES: This exemption is effective from July 1, 2013 through June...

"I just wanted to get away": An analysis of spring breakers' travel motivations

Treesearch

Nuno F. Ribeiro; Paul E. Durrenberger; Careen M. Yarnal; Garry E. Chick

2010-01-01

Scholarly research on Spring Break has grown substantially and has often associated spring breakers' motivations with a number of risky behaviors. Recent research, however, has challenged these assumptions. The purpose of this study was to examine spring breakers' motivations for going on Spring Break. Unlike the media portrayal of Spring Break as a time of...

E-mail, decisional styles, and rest breaks.

PubMed

Baker, James R; Phillips, James G

2007-10-01

E-mail is a common but problematic work application. A scale was created to measure tendencies to use e-mail to take breaks (e-breaking); and self-esteem and decisional style (vigilance, procrastination, buck-passing, hypervigilance) were used to predict the self-reported and actual e-mail behaviors of 133 participants (students and marketing employees). Individuals who were low in defensive avoidance (buck-passing) engaged in more e-mailing per week, both in time spent on e-mail and message volume. E-breakers were more likely to engage in behavioral procrastination and spent more time on personal e-mail.

Rapid MCNP simulation of DNA double strand break (DSB) relative biological effectiveness (RBE) for photons, neutrons, and light ions.

PubMed

Stewart, Robert D; Streitmatter, Seth W; Argento, David C; Kirkby, Charles; Goorley, John T; Moffitt, Greg; Jevremovic, Tatjana; Sandison, George A

2015-11-07

To account for particle interactions in the extracellular (physical) environment, information from the cell-level Monte Carlo damage simulation (MCDS) for DNA double strand break (DSB) induction has been integrated into the general purpose Monte Carlo N-particle (MCNP) radiation transport code system. The effort to integrate these models is motivated by the need for a computationally efficient model to accurately predict particle relative biological effectiveness (RBE) in cell cultures and in vivo. To illustrate the approach and highlight the impact of the larger scale physical environment (e.g. establishing charged particle equilibrium), we examined the RBE for DSB induction (RBEDSB) of x-rays, (137)Cs γ-rays, neutrons and light ions relative to γ-rays from (60)Co in monolayer cell cultures at various depths in water. Under normoxic conditions, we found that (137)Cs γ-rays are about 1.7% more effective at creating DSB than γ-rays from (60)Co (RBEDSB  =  1.017) whereas 60-250 kV x-rays are 1.1 to 1.25 times more efficient at creating DSB than (60)Co. Under anoxic conditions, kV x-rays may have an RBEDSB up to 1.51 times as large as (60)Co γ-rays. Fission neutrons passing through monolayer cell cultures have an RBEDSB that ranges from 2.6 to 3.0 in normoxic cells, but may be as large as 9.93 for anoxic cells. For proton pencil beams, Monte Carlo simulations suggest an RBEDSB of about 1.2 at the tip of the Bragg peak and up to 1.6 a few mm beyond the Bragg peak. Bragg peak RBEDSB increases with decreasing oxygen concentration, which may create opportunities to apply proton dose painting to help address tumor hypoxia. Modeling of the particle RBE for DSB induction across multiple physical and biological scales has the potential to aid in the interpretation of laboratory experiments and provide useful information to advance the safety and effectiveness of hadron therapy in the treatment of cancer.

Spatial Complexity Due to Bulk Electronic Liquid Crystals in Superconducting Dy-Bi2212

NASA Astrophysics Data System (ADS)

Carlson, Erica; Phillabaum, Benjamin; Dahmen, Karin

2012-02-01

Surface probes such as scanning tunneling microscopy (STM) have detected complex electronic patterns at the nanoscale in many high temperature superconductors. In cuprates, the pattern formation is associated with the pseudogap phase, a precursor to the high temperature superconducting state. Rotational symmetry breaking of the host crystal (i.e. from C4 to C2) in the form of electronic nematicity has recently been proposed as a unifying theme of the pseudogap phase [Lawler Nature 2010]. However, the fundamental physics governing the nanoscale pattern formation has not yet been identified. Here we use universal cluster properties extracted from STM studies of cuprate superconductors to identify the funda- mental physics controlling the complex pattern formation. We find that due to a delicate balance between disorder, interactions, and material anisotropy, the rotational symmetry breaking is fractal in nature, and that the electronic liquid crystal extends throughout the bulk of the material.

Lateralization as a symmetry breaking process in birdsong

NASA Astrophysics Data System (ADS)

Trevisan, M. A.; Cooper, B.; Goller, F.; Mindlin, G. B.

2007-03-01

The singing by songbirds is a most convincing example in the animal kingdom of functional lateralization of the brain, a feature usually associated with human language. Lateralization is expressed as one or both of the bird’s sound sources being active during the vocalization. Normal songs require high coordination between the vocal organ and respiratory activity, which is bilaterally symmetric. Moreover, the physical and neural substrate used to produce the song lack obvious asymmetries. In this work we show that complex spatiotemporal patterns of motor activity controlling airflow through the sound sources can be explained in terms of spontaneous symmetry breaking bifurcations. This analysis also provides a framework from which to study the effects of imperfections in the system’ s symmetries. A physical model of the avian vocal organ is used to generate synthetic sounds, which allows us to predict acoustical signatures of the song and compare the predictions of the model with experimental data.

A Model of Direct Gauge Mediation of Supersymmetry Breaking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murayama, H.

1997-07-01

We present the first phenomenologically viable model of gauge meditation of supersymmetry breaking without a messenger sector or gauge singlet fields. The standard model gauge groups couple directly to the sector which breaks supersymmetry dynamically. Despite the direct coupling, it can preserve perturbative gauge unification thanks to the inverted hierarchy mechanism. There is no dangerous negative contribution to m{sup 2}{sub {tilde q}} , m{sup 2}{sub {tilde l}} due to two-loop renormalization group equation. The potentially nonuniversal supergravity contribution to m{sup 2}{sub {tilde q}} and m{sup 2}{sub {tilde l}} can be suppressed enough. The model is completely chiral, and one doesmore » not need to forbid mass terms for the messenger fields by hand. Cosmology of the model is briefly discussed. {copyright} {ital 1997} {ital The American Physical Society}« less

Structure of 10Be and 16C nuclei via break-up reactions studied with the 4π Chimera array

NASA Astrophysics Data System (ADS)

Dell'Aquila, D.; Acosta, L.; Amorini, F.; Andolina, R.; Auditore, L.; Berceanu, I.; Cardella, G.; Chatterjiee, M. B.; De Filippo, E.; Francalanza, L.; Gnoffo, B.; Grzeszczuk, A.; Lanzalone, G.; Lombardo, I.; Martorana, N.; Minniti, T.; Pagano, A.; Pagano, E. V.; Papa, M.; Pirrone, S.; Politi, G.; Pop, A.; Porto, F.; Quattrocchi, L.; Rizzo, F.; Rosato, E.; Russotto, P.; Trifirò, A.; Trimarchi, M.; Verde, G.; Vigilante, M.

2018-01-01

The study of cluster states in neutron-rich Be and C isotopes is a subject of interest in Nuclear Physics. These states should be characterized by high deformation where α-clusters are bounded by valence neutrons. We performed a spectroscopic study of 10Be and 16C isotopes via projectile break-up reactions, by using radioactive beams produced at the INFN-LNS FRIBs facility and the Chimera 4π array. The possible evidence of a new 10Be state at 13.5 MeV excitation energy was found in the 6He+4He disintegration channel. The spectroscopy of 16C was studied via the 6He+10Be break-up channel; in this case we found the indication of a possible new state at about 20.6 MeV.

Adipose Tissue Responses to Breaking Sitting in Men and Women with Central Adiposity.

PubMed

Chen, Yung-Chih; Betts, James A; Walhin, Jean-Philippe; Thompson, Dylan

2018-04-27

Breaking prolonged sitting reduces postprandial glucose and insulin concentrations and influences skeletal muscle molecular signalling pathways but it is unknown whether breaking sitting also affects adipose tissue. Eleven central overweight participants (7 men and 4 post-menopausal women) aged 50 ± 5 years (means ± SD) completed two mixed-meal feeding trials (PROLONGED SITTING versus BREAKING SITTING) in a randomised, counterbalanced design. The BREAKING SITTING intervention comprised walking for 2 min every 20 min over 5.5 h. Blood samples were taken at regular intervals to examine metabolic biomarkers and adipokine concentrations. Adipose tissue samples were taken at baseline and at 5.5 h to examine changes in mRNA expression and secretion of selected adipokines ex-vivo. Postprandial glycaemia and insulinaemia were attenuated by approximately 50% and 40% in BREAKING SITTING compared to PROLONGED SITTING (iAUC: 359 ± 117 versus 697 ± 218 mmol·330 min·L, p = 0.001 and 202 ± 71 versus 346 ± 150 nmol·330 min·L, p = 0.001, respectively). Despite these pronounced and sustained differences in postprandial glucose and insulin concentrations, adipose tissue mRNA expression for various genes (IL-6, leptin, adiponectin, PDK4, IRS1/2, PI3K and Akt1, etc.) and ex-vivo adipose tissue secretion of IL-6, leptin and adiponectin were not different between trials. This study demonstrates that breaking sitting with short bouts of physical activity has very pronounced effects on systemic postprandial glucose and insulin concentrations but this does not translate into corresponding effects within adipose tissue.

Validation and Comparison of Accelerometers Worn on the Hip, Thigh, and Wrists for Measuring Physical Activity and Sedentary Behavior.

PubMed

Montoye, Alexander H K; Pivarnik, James M; Mudd, Lanay M; Biswas, Subir; Pfeiffer, Karin A

2016-01-01

Recent evidence suggests that physical activity (PA) and sedentary behavior (SB) exert independent effects on health. Therefore, measurement methods that can accurately assess both constructs are needed. To compare the accuracy of accelerometers placed on the hip, thigh, and wrists, coupled with machine learning models, for measurement of PA intensity category (SB, light-intensity PA [LPA], and moderate- to vigorous-intensity PA [MVPA]) and breaks in SB. Forty young adults (21 female; age 22.0 ± 4.2 years) participated in a 90-minute semi-structured protocol, performing 13 activities (three sedentary, 10 non-sedentary) for 3-10 minutes each. Participants chose activity order, duration, and intensity. Direct observation (DO) was used as a criterion measure of PA intensity category, and transitions from SB to a non-sedentary activity were breaks in SB. Participants wore four accelerometers (right hip, right thigh, and both wrists), and a machine learning model was created for each accelerometer to predict PA intensity category. Sensitivity and specificity for PA intensity category classification were calculated and compared across accelerometers using repeated measures analysis of variance, and the number of breaks in SB was compared using repeated measures analysis of variance. Sensitivity and specificity values for the thigh-worn accelerometer were higher than for wrist- or hip-worn accelerometers, > 99% for all PA intensity categories. Sensitivity and specificity for the hip-worn accelerometer were 87-95% and 93-97%. The left wrist-worn accelerometer had sensitivities and specificities of > 97% for SB and LPA and 91-95% for MVPA, whereas the right wrist-worn accelerometer had sensitivities and specificities of 93-99% for SB and LPA but 67-84% for MVPA. The thigh-worn accelerometer had high accuracy for breaks in SB; all other accelerometers overestimated breaks in SB. Coupled with machine learning modeling, the thigh-worn accelerometer should be considered when objectively assessing PA and SB.

Effect of hand paddles and parachute on butterfly coordination.

PubMed

Telles, Thiago; Barroso, Renato; Barbosa, Augusto Carvalho; Salgueiro, Diego Fortes de Souza; Colantonio, Emilson; Andries Júnior, Orival

2015-01-01

This study investigated the effects of hand paddles, parachute and hand paddles plus parachute on the inter-limb coordination of butterfly swimming. Thirteen male swimmers were evaluated in four random maximal intensity conditions: without equipment, with hand paddles, with parachute and with hand paddles + parachute. Arm and leg stroke phases were identified by 2D video analysis to calculate the total time gap (T1: time between hands' entry in the water and high break-even point of the first undulation; T2: time between the beginning of the hand's backward movement and low break-even point of the first undulation; T3: time between the hand's arrival in a vertical plane to the shoulders and high break-even point of the second undulation; T4: time between the hand's release from the water and low break-even point of the second undulation). The swimming velocity was reduced and T1, T2 and T3 increased in parachute and hand paddles + parachute. No changes were observed in T4. Total time gap decreased in parachute and hand paddles + parachute. It is concluded that hand paddles do not influence the arm-to-leg coordination in butterfly, while parachute and hand paddles + parachute do change it, providing a greater propulsive continuity.

Kinetics and Photochemistry of Ruthenium Bisbipyridine Diacetonitrile Complexes: An Interdisciplinary Inorganic and Physical Chemistry Laboratory Exercise.

PubMed

Rapp, Teresa L; Phillips, Susan R; Dmochowski, Ivan J

2016-12-13

The study of ruthenium polypyridyl complexes can be widely applied across disciplines in the undergraduate curriculum. Ruthenium photochemistry has advanced many fields including dye-sensitized solar cells, photoredox catalysis, light-driven water oxidation, and biological electron transfer. Equally promising are ruthenium polypyridyl complexes that provide a sterically bulky, photolabile moiety for transiently "caging" biologically active molecules. Photouncaging involves the use of visible (1-photon) or near-IR (2-photon) light to break one or more bonds between ruthenium and coordinated ligand(s), which can occur on short time scales and in high quantum yields. In this work we demonstrate the use of a model "caged" acetonitrile complex, Ru(2,2'-bipyridine) 2 (acetonitrile) 2 , or RuMeCN in an advanced synthesis and physical chemistry laboratory. Students made RuMeCN in an advanced synthesis laboratory course and performed UV-vis spectroscopy and electrochemistry. The following semester students investigated RuMeCN photolysis kinetics in a physical chemistry laboratory. These two exercises may also be combined to create a 2-week module in an advanced undergraduate laboratory course.

Petascale Kinetic Simulations in Space Sciences: New Simulations and Data Discovery Techniques and Physics Results

NASA Astrophysics Data System (ADS)

Karimabadi, Homa

2012-03-01

Recent advances in simulation technology and hardware are enabling breakthrough science where many longstanding problems can now be addressed for the first time. In this talk, we focus on kinetic simulations of the Earth's magnetosphere and magnetic reconnection process which is the key mechanism that breaks the protective shield of the Earth's dipole field, allowing the solar wind to enter the Earth's magnetosphere. This leads to the so-called space weather where storms on the Sun can affect space-borne and ground-based technological systems on Earth. The talk will consist of three parts: (a) overview of a new multi-scale simulation technique where each computational grid is updated based on its own unique timestep, (b) Presentation of a new approach to data analysis that we refer to as Physics Mining which entails combining data mining and computer vision algorithms with scientific visualization to extract physics from the resulting massive data sets. (c) Presentation of several recent discoveries in studies of space plasmas including the role of vortex formation and resulting turbulence in magnetized plasmas.

Kinetics and Photochemistry of Ruthenium Bisbipyridine Diacetonitrile Complexes: An Interdisciplinary Inorganic and Physical Chemistry Laboratory Exercise

PubMed Central

2016-01-01

The study of ruthenium polypyridyl complexes can be widely applied across disciplines in the undergraduate curriculum. Ruthenium photochemistry has advanced many fields including dye-sensitized solar cells, photoredox catalysis, light-driven water oxidation, and biological electron transfer. Equally promising are ruthenium polypyridyl complexes that provide a sterically bulky, photolabile moiety for transiently “caging” biologically active molecules. Photouncaging involves the use of visible (1-photon) or near-IR (2-photon) light to break one or more bonds between ruthenium and coordinated ligand(s), which can occur on short time scales and in high quantum yields. In this work we demonstrate the use of a model “caged” acetonitrile complex, Ru(2,2′-bipyridine)2(acetonitrile)2, or RuMeCN in an advanced synthesis and physical chemistry laboratory. Students made RuMeCN in an advanced synthesis laboratory course and performed UV–vis spectroscopy and electrochemistry. The following semester students investigated RuMeCN photolysis kinetics in a physical chemistry laboratory. These two exercises may also be combined to create a 2-week module in an advanced undergraduate laboratory course. PMID:28649139

Biological energy sources: the surface energy and the physical chemistry of water. Examples from studies on muscle contraction.

PubMed

Widdas, W F; Baker, G F

2004-01-01

The physical chemistry of water at nanometre dimensions was used to explain the conformational changes and water breaking properties of the glucose transporter protein (GLUTI) in human erythrocytes more than ten years ago. The energy for this hidden work arises from cycles of evaporation and condensation of water within the cells but was several times larger than resting metabolism. Physical chemical principles can quantify the hidden work done and demonstrate that a significant source of energy is available, which is free of the metabolic energy derived from the hydrolysis of ATP. Therefore, a more widespread biological use of this "free" energy source was probable and a working hypothesis, which applied this energy to supplement the work derived from ATP hydrolysis in muscle, was proposed. The scheme gives a complete explanation for the unexpected and novel findings in skeletal muscle reported from Italy. The problem of using two energy sources and the novel properties of water at nanometer dimensions as they would apply in muscle are briefly discussed but they merit further interdisciplinary studies.

Quantum Hall physics: Hierarchies and conformal field theory techniques

NASA Astrophysics Data System (ADS)

Hansson, T. H.; Hermanns, M.; Simon, S. H.; Viefers, S. F.

2017-04-01

The fractional quantum Hall effect, being one of the most studied phenomena in condensed matter physics during the past 30 years, has generated many ground-breaking new ideas and concepts. Very early on it was realized that the zoo of emerging states of matter would need to be understood in a systematic manner. The first attempts to do this, by Haldane and Halperin, set an agenda for further work which has continued to this day. Since that time the idea of hierarchies of quasiparticles condensing to form new states has been a pillar of our understanding of fractional quantum Hall physics. In the 30 years that have passed since then, a number of new directions of thought have advanced our understanding of fractional quantum Hall states and have extended it in new and unexpected ways. Among these directions is the extensive use of topological quantum field theories and conformal field theories, the application of the ideas of composite bosons and fermions, and the study of non-Abelian quantum Hall liquids. This article aims to present a comprehensive overview of this field, including the most recent developments.

My Oar Keeps Breaking: How to Move Your Part of the Program Forward

DTIC Science & Technology

2016-02-01

53 Defense AT&L: January–February 2016 My Oar Keeps Breaking How to Move Your Part of the Program Forward Chad Millette Millette is a retired...the water to influence the program’s speed or direction. I would tell people that I felt like every time I stuck my oar in the water, it would break ...I would then go back and get another one and stick it in the water, only to have it break again. I was pretty proud of myself for coming up with

Improvement of flavor and viscosity in hot and cold break tomato juice and sauce by peel removal.

PubMed

Mirondo, Rita; Barringer, Sheryl

2015-01-01

Tomatoes are typically not peeled before being made into juice but the peels contain enzymes that affect the odor, flavor, and viscosity of the juice. The peels are removed in the finisher, but their presence during the break process may affect quality. Juice was processed from peeled and unpeeled tomatoes using hot or cold break. The juices were pasteurized by high temperature short time (HTST), low temperature long time (LTLT), or with a retort. The control samples were treated with 10% calcium chloride to stop enzymatic activity in the juice. Sauce was made from juice and the tomato products were analyzed for volatiles, color, viscosity, and by sensory. Cold break juice made with peel contained higher levels of some lipoxygenase-, carotenoid-, and amino acid-derived volatiles, than the juice made without peel. Because of the lack of enzyme activity, hot break juices had lower levels of these volatiles and there was no significant difference between hot break juices made with and without peel. CaCl2 -treated and HTST juice had higher levels of most of the volatiles than LTLT, including the lipoxygenase-derived volatiles. The presence of peel produced a significant decrease in the viscosity of the cold break juice and sauce. There was no significant difference in the hue angle, total soluble solids, pH, titratable acidity, and vitamin C for most of the treatments. The texture, flavor, and overall liking of cold break juice made without peel were preferred over cold break juice made with peel whereas the color was less preferred. Between the sauces no significant differences in preference were obtained. © 2014 Institute of Food Technologists®

Planck 2010: From the Planck Scale to the ElectroWeak Scale (Part 9)

ScienceCinema

None

2018-06-27

"Planck 2010: From the Planck Scale to the ElectroWeak Scale". The conference will be the twelfth one in a series of meetings on physics beyond the Standard Model, organized jointly by several European groups: Bonn, CERN, Ecole Polytechnique, ICTP, Madrid, Oxford, Padua, Pisa, SISSA and Warsaw as part of activities in the framework of the European network UNILHC. The main topic covered will be "Supersymmetry", with discussions on: supergravity and string phenomenology, extra dimensions, electroweak symmetry breaking, LHC and Tevatron physics, collider physics, flavor and neutrino physics, astroparticle and cosmology, gravity and holography, and strongly coupled physics and CFT.

Planck 2010: From the Planck Scale to the ElectroWeak Scale (Part 5)

ScienceCinema

None

2018-06-27

"Planck 2010: From the Planck Scale to the ElectroWeak Scale". The conference will be the twelfth one in a series of meetings on physics beyond the Standard Model, organized jointly by several European groups: Bonn, CERN, Ecole Polytechnique, ICTP, Madrid, Oxford, Padua, Pisa, SISSA and Warsaw as part of activities in the framework of the European network UNILHC. The main topic covered will be "Supersymmetry", with discussions on: supergravity and string phenomenology, extra dimensions, electroweak symmetry breaking, LHC and Tevatron physics, collider physics, flavor and neutrino physics, astroparticle and cosmology, gravity and holography, and strongly coupled physics and CFT.

Planck 2010: From the Planck Scale to the ElectroWeak Scale (Part 6)

ScienceCinema

None

2018-06-28

"Planck 2010: From the Planck Scale to the ElectroWeak Scale". The conference will be the twelfth one in a series of meetings on physics beyond the Standard Model, organized jointly by several European groups: Bonn, CERN, Ecole Polytechnique, ICTP, Madrid, Oxford, Padua, Pisa, SISSA and Warsaw as part of activities in the framework of the European network UNILHC. The main topic covered will be "Supersymmetry", with discussions on: supergravity and string phenomenology, extra dimensions, electroweak symmetry breaking, LHC and Tevatron physics, collider physics, flavor and neutrino physics, astroparticle and cosmology, gravity and holography, and strongly coupled physics and CFT.

Large-wave simulation of spilling breaking and undertow current over constant slope beach

NASA Astrophysics Data System (ADS)

Dimas, Athanassios; Kolokythas, Gerasimos; Dimakopoulos, Aggelos

2011-11-01

The three-dimensional, free-surface flow, developing by the propagation of nonlinear breaking waves over a constant slope bed, is numerically simulated. The main objective is to investigate the effect of spilling breaking on the characteristics of the induced undertow current by performing large-wave simulations (LWS) based on the numerical solution of the Navier-Stokes equations subject to the fully nonlinear free-surface boundary conditions and the appropriate bottom, inflow and outflow boundary conditions. The equations are properly transformed so that the computational domain becomes time-independent. In the present study, the case of incoming waves with wavelength to inflow depth ratio λ/ d ~ 6.6 and wave steepness H/ λ ~0.025, over bed of slope tan β = 1/35, is investigated. The LWS predicts satisfactorily breaking parameters - height and depth - and wave dissipation in the surf zone, in comparison to experimental data. In the corresponding LES, breaking height and depth are smaller and wave dissipation in the surf zone is weaker. For the undertow current, it is found that it is induced by the breaking process at the free surface, while its strength is controlled by the bed shear stress. Finally, the amplitude of the bed shear stress increases substantially in the breaking zone, becoming up to six times larger than the respective amplitude at the outer region.

Anomalous Nernst effect in type-II Weyl semimetals

NASA Astrophysics Data System (ADS)

Saha, Subhodip; Tewari, Sumanta

2018-01-01

Topological Weyl semimetals (WSM), a new state of quantum matter with gapless nodal bulk spectrum and open Fermi arc surface states, have recently sparked enormous interest in condensed matter physics. Based on the symmetry and fermiology, it has been proposed that WSMs can be broadly classified into two types, type-I and type-II Weyl semimetals. While the undoped, conventional, type-I WSMs have point like Fermi surface and vanishing density of states (DOS) at the Fermi energy, the type-II Weyl semimetals break Lorentz symmetry explicitly and have tilted conical spectra with electron and hole pockets producing finite DOS at the Fermi level. The tilted conical spectrum and finite DOS at Fermi level in type-II WSMs have recently been shown to produce interesting effects such as a chiral anomaly induced longitudinal magnetoresistance that is strongly anisotropic in direction and a novel anomalous Hall effect. In this work, we consider the anomalous Nernst effect in type-II WSMs in the absence of an external magnetic field using the framework of semi-classical Boltzmann theory. Based on both a linearized model of time-reversal breaking WSM with a higher energy cut-off and a more realistic lattice model, we show that the anomalous Nernst response in these systems is strongly anisotropic in space, and can serve as a reliable signature of type-II Weyl semimetals in a host of magnetic systems with spontaneously broken time reversal symmetry.

A narrative review of manual muscle testing and implications for muscle testing research

PubMed Central

Conable, Katharine M.; Rosner, Anthony L.

2011-01-01

Objective Manual muscle testing (MMT) is used for a variety of purposes in health care by medical, osteopathic, chiropractic, physical therapy, rehabilitation, and athletic training professionals. The purpose of this study is to provide a narrative review of variations in techniques, durations, and forces used in MMT putting applied kinesiology (AK) muscle testing in context and highlighting aspects of muscle testing important to report in MMT research. Method PubMed, the Collected Papers of the International College of Applied Kinesiology–USA, and related texts were searched on the subjects of MMT, maximum voluntary isometric contraction testing, and make/break testing. Force parameters (magnitude, duration, timing of application), testing variations of MMT, and normative data were collected and evaluated. Results “Break” tests aim to evaluate the muscle's ability to resist a gradually increasing pressure and may test different aspects of neuromuscular control than tests against fixed resistances. Applied kinesiologists use submaximal manual break tests and a binary grading scale to test short-term changes in muscle function in response to challenges. Many of the studies reviewed were not consistent in reporting parameters for testing. Conclusions To increase the chances for replication, studies using MMT should specify parameters of the tests used, such as exact procedures and instrumentation, duration of test, peak force, and timing of application of force. PMID:22014904

Evaluation of the Comet Assay for Assessing the Dose-Response Relationship of DNA Damage Induced by Ionizing Radiation

PubMed Central

Wang, Yan; Xu, Chang; Du, Li Qing; Cao, Jia; Liu, Jian Xiang; Su, Xu; Zhao, Hui; Fan, Fei-Yue; Wang, Bing; Katsube, Takanori; Fan, Sai Jun; Liu, Qiang

2013-01-01

Dose- and time-response curves were combined to assess the potential of the comet assay in radiation biodosimetry. The neutral comet assay was used to detect DNA double-strand breaks in lymphocytes caused by γ-ray irradiation. A clear dose-response relationship with DNA double-strand breaks using the comet assay was found at different times after irradiation (p < 0.001). A time-response relationship was also found within 72 h after irradiation (p < 0.001). The curves for DNA double-strand breaks and DNA repair in vitro of human lymphocytes presented a nice model, and a smooth, three-dimensional plane model was obtained when the two curves were combined. PMID:24240807

Camden active spaces: Does the construction of active school playgrounds influence children's physical activity levels? A longitudinal quasi-experiment protocol

PubMed Central

Smith, Lee; Kipps, Courtney; Aggio, Daniel; Fox, Paul; Robinson, Nigel; Trend, Verena; Munnery, Suzie; Kelly, Barry; Hamer, Mark

2014-01-01

Introduction Physical activity is essential for every facet of children's health. However, physical activity levels in British children are low. The school environment is a promising setting to increase children's physical activity but limited empirical evidence exists on how a change in the outdoor physical school environment influences physical activity behaviour. The London Borough of Camden is redesigning seven existing school playgrounds to engage children to become more physically active. The primary aim of this project is to evaluate the impact of the redesigned playgrounds on children's physical activity, well-being and physical function/fitness. Method and analysis This project will use a longitudinal quasi-experimental design. Seven experimental schools and one control school will take part. One baseline data collection session and two follow-ups will be carried out. Between baseline and follow-up, the experimental school playgrounds will be redesigned. At baseline, a series of fitness tests, anthropometric and questionnaire measurements, and 7-day objective physical activity monitoring (Actigraph accelerometer) will be carried out on children (aged 5–16 years). This will be repeated at follow-up. Changes in overall physical activity levels and levels during different times of the day (eg, school breaks) will be examined. Multilevel regression modelling will be used to analyse the data. Ethics and dissemination The results of this study will be disseminated through peer-review publications and scientific presentations. Ethical approval was obtained through the University College London Research Ethics Committee (Reference number: 4400/002). PMID:25232566

Supercontinent break-up: Causes and consequences

NASA Astrophysics Data System (ADS)

Li, Z. X.

2014-12-01

Supercontinent break-up has most commonly been linked to plume or superplume events, and/or supercontinent thermal insulation, but precise mechanisms are yet to be worked out. Even less know is if and what roles other factors may play. Key factors likely include gravitational force due to the continental superswell driven by both the lower-mantle superplume and continental thermal insulation, mental convention driven by the superplume and individual plumes atop the superplume, assisted by thermal/magmatic weakening of the supercontinent interior (both plume heat and thermal insulation heat). In addition, circum-supercontinent slab downwelling may not only drive the formation of the antipodal superplumes (thus the break-up of the supercontinent), the likely roll-back of the subduction system would also create extension within the supercontinent, facilitating supercontinent break-up. Consequences of supercontinent break-up include long-term sea-level rise, climatic changes due to changes in ocean circulation pattern and carbon cycle, and biodiversification. It has long been demonstrated that the existence of the supercontinent Pangea corresponds to a long-term sea-level drop, whereas the break-up of the supercontinent corresponds to a long-term sea-level rise (170 m higher than it is today). A recent analysis of Neoproterozoic sedimentary facies illustrates that the time of Neoproterozoic supercontinent Rodinia corresponds to a low in the percentage of deep marine facies occurrence, whereas the time of Rodinia break-up corresponds to a significantly higher percentage of deep marine facies occurrence. The long-tern sea-level drop during supercontinent times were likely caused by both plume/superplume dynamic topography and an older mean age of the oceanic crust, whereas long-tern sea-level rise during supercontinent break-up (720-580 Ma for Rodinia and Late Jurassic-Cretaceous for Pangea) likely corresponds to an younger mean age of the oceanic crust, massive plume-induced magmatism in the oceans, and perhaps the effect of continents drifting away from a weakening sub-supercontinent superplume.

The Emergence of Dirac points in Photonic Crystals with Mirror Symmetry

PubMed Central

He, Wen-Yu; Chan, C. T.

2015-01-01

We show that Dirac points can emerge in photonic crystals possessing mirror symmetry when band gap closes. The mechanism of generating Dirac points is discussed in a two-dimensional photonic square lattice, in which four Dirac points split out naturally after the touching of two bands with different parity. The emergence of such nodal points, characterized by vortex structure in momentum space, is attributed to the unavoidable band crossing protected by mirror symmetry. The Dirac nodes can be unbuckled through breaking the mirror symmetry and a photonic analog of Chern insulator can be achieved through time reversal symmetry breaking. Breaking time reversal symmetry can lead to unidirectional helical edge states and breaking mirror symmetry can reduce the band gap to amplify the finite size effect, providing ways to engineer helical edge states. PMID:25640993

Aggression, academic behaviors, and popularity perceptions among boys of color during the transition to middle school.

PubMed

Xie, Hongling; Dawes, Molly; Wurster, Tabitha J; Shi, Bing

2013-01-01

The transition to middle school often presents behavioral and academic challenges to youths. Boys of color (i.e., African American and Hispanic in this study) may be especially vulnerable. In this study, peer nominations of aggressive and academic behaviors as well as youths' perceptions of how these behaviors were related to popularity in peer networks were obtained from the spring semester of fifth grade through the spring semester of seventh grade, with the transition occurring as the students entered the sixth grade. The sample included 188 boys (71 Caucasian, 90 African American, and 27 Hispanic) from an urban school district in the northeastern United States. Trajectory analyses showed that African American boys scored lower in studentship and higher in rule-breaking and aggressive (both physical and social) behaviors prior to the transition, and such differences among ethnic groups were largely maintained during the transition. Hispanic boys displayed decreases in their studentship during the transition. African American boys' perception of how studentship affects popularity was more positive than other boys prior to the transition, but it decreased during the transition. African American boys also endorsed rule breaking and physical and social aggression more positively for popularity prior to the transition, whereas Caucasian and Hispanic boys' endorsement increased during the transition and eventually caught up with those of African American boys in seventh grade. A positive within-individual association was found between youths' popularity perception and their behavior for studentship, rule breaking, and physical aggression, which did not differ by ethnicity. © 2013 American Orthopsychiatric Association.

The Potential Impact of Displacing Sedentary Time in Adults with Type 2 Diabetes

PubMed Central

FALCONER, CATHERINE L.; PAGE, ANGIE S.; ANDREWS, ROB C.; COOPER, ASHLEY R.

2015-01-01

ABSTRACT Purpose Sedentary time, in particular, prolonged unbroken sedentary time, is detrimental to health and displaces time spent in either light or moderate intensity physical activity. This cross-sectional study aimed to identify the potential impact of reallocating time from sedentary behaviors to more active behaviors on measures of body composition and metabolic health in people with type 2 diabetes. Methods Participants were 519 adults with newly diagnosed type 2 diabetes who had been recruited to the Early Activity in Diabetes (Early ACTID) randomized controlled trial. Waist-worn accelerometers were used to obtain objective measurement of sedentary time, light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) at baseline alongside clinical measurements and fasting blood samples to determine cholesterol, triglycerides, HOMA-IR, and glucose. Isotemporal substitution modeling was performed to determine the potential impact of reallocating 30 min of sedentary time accumulated in a single bout (long bout) with 30 min of interrupted sedentary time, LPA, or MVPA. Results Sedentary time accounted for 65% of the waking day, of which 45% was accumulated in prolonged (≥30 min) bouts. Reallocation of 30 min of long-bout sedentary time with 30 min of short-bout sedentary time was associated with lower body mass index (BMI) (adjusted β, −0.60; 95% confidence interval [CI], −1.00, −0.21) and waist circumference (WC) (adjusted β, −1.16; 95% CI, −2.08, −0.25). Stronger effects were seen for LPA and MVPA. Reallocation of 30 min of long-bout sedentary time with LPA was associated with higher HDL-cholesterol (adjusted β, 0.02; 95% CI, 0.00–0.03 mmol·L−1). Conclusions Encouraging adults with newly diagnosed type 2 diabetes to break up prolonged periods of sedentary time may be an effective strategy for improving body composition and metabolic health. PMID:26378943

Vortex-induced suspension of sediment in the surf zone

NASA Astrophysics Data System (ADS)

Otsuka, Junichi; Saruwatari, Ayumi; Watanabe, Yasunori

2017-12-01

A major mechanism of sediment suspension by organized vortices produced under violent breaking waves in the surf zone was identified through physical and computational experiments. Counter-rotating flows within obliquely descending eddies produced between adjacent primary roller vortices induce transverse convergent near-bed flows, driving bed load transport to form regular patterns of transverse depositions. The deposited sediment is then rapidly ejected by upward carrier flows induced between the vortices. This mechanism of vortex-induced suspension is supported by experimental evidence that coherent sediment clouds are ejected where the obliquely descending eddies reach the sea bed after the breaking wave front has passed. In addition to the effects of settling and turbulent diffusion caused by breaking waves, the effect of the vortex-induced flows was incorporated into a suspension model on the basis of vorticity dynamics and parametric characteristics of transverse flows in breaking waves. The model proposed here reasonably predicts an exponential attenuation of the measured sediment concentration due to violent plunging waves and significantly improves the underprediction of the concentration produced by previous models.

Spontaneous mirror-symmetry breaking induces inverse energy cascade in 3D active fluids

PubMed Central

Słomka, Jonasz; Dunkel, Jörn

2017-01-01

Classical turbulence theory assumes that energy transport in a 3D turbulent flow proceeds through a Richardson cascade whereby larger vortices successively decay into smaller ones. By contrast, an additional inverse cascade characterized by vortex growth exists in 2D fluids and gases, with profound implications for meteorological flows and fluid mixing. The possibility of a helicity-driven inverse cascade in 3D fluids had been rejected in the 1970s based on equilibrium-thermodynamic arguments. Recently, however, it was proposed that certain symmetry-breaking processes could potentially trigger a 3D inverse cascade, but no physical system exhibiting this phenomenon has been identified to date. Here, we present analytical and numerical evidence for the existence of an inverse energy cascade in an experimentally validated 3D active fluid model, describing microbial suspension flows that spontaneously break mirror symmetry. We show analytically that self-organized scale selection, a generic feature of many biological and engineered nonequilibrium fluids, can generate parity-violating Beltrami flows. Our simulations further demonstrate how active scale selection controls mirror-symmetry breaking and the emergence of a 3D inverse cascade. PMID:28193853

On the kinematic criterion for the inception of breaking in surface gravity waves: Fully nonlinear numerical simulations and experimental verification

NASA Astrophysics Data System (ADS)

Khait, A.; Shemer, L.

2018-05-01

The evolution of unidirectional wave trains containing a wave that gradually becomes steep is evaluated experimentally and numerically using the Boundary Element Method (BEM). The boundary conditions for the nonlinear numerical simulations corresponded to the actual movements of the wavemaker paddle as recorded in the physical experiments, allowing direct comparison between the measured in experiments' characteristics of the wave train and the numerical predictions. The high level of qualitative and quantitative agreement between the measurements and simulations validated the kinematic criterion for the inception of breaking and the location of the spilling breaker, on the basis of the BEM computations and associated experiments. The breaking inception is associated with the fluid particle at the crest of the steep wave that has been accelerated to match and surpass the crest velocity. The previously observed significant slow-down of the crest while approaching breaking is verified numerically; both narrow-/broad-banded wave trains are considered. Finally, the relative importance of linear and nonlinear contributions is analyzed.

Break-ups Before Marriage: The End of 103 Affairs

ERIC Educational Resources Information Center

Hill, Charles T.; And Others

1976-01-01

Factors that predicted breakups before marriage, investigated as part of a two-year study of dating relationships among college students include unequal involvement in the relationship and discrepant age, educational aspirations, intelligence, and physical attractiveness. (Author/AM)

Quantifying the behavior of price dynamics at opening time in stock market

NASA Astrophysics Data System (ADS)

Ochiai, Tomoshiro; Takada, Hideyuki; Nacher, Jose C.

2014-11-01

The availability of huge volume of financial data has offered the possibility for understanding the markets as a complex system characterized by several stylized facts. Here we first show that the time evolution of the Japan’s Nikkei stock average index (Nikkei 225) futures follows the resistance and breaking-acceleration effects when the complete time series data is analyzed. However, in stock markets there are periods where no regular trades occur between the close of the market on one day and the next day’s open. To examine these time gaps we decompose the time series data into opening time and intermediate time. Our analysis indicates that for the intermediate time, both the resistance and the breaking-acceleration effects are still observed. However, for the opening time there are almost no resistance and breaking-acceleration effects, and volatility is always constantly high. These findings highlight unique dynamic differences between stock markets and forex market and suggest that current risk management strategies may need to be revised to address the absence of these dynamic effects at the opening time.

In Vivo Anomalous Diffusion and Weak Ergodicity Breaking of Lipid Granules

NASA Astrophysics Data System (ADS)

Jeon, Jae-Hyung; Tejedor, Vincent; Burov, Stas; Barkai, Eli; Selhuber-Unkel, Christine; Berg-Sørensen, Kirstine; Oddershede, Lene; Metzler, Ralf

2011-01-01

Combining extensive single particle tracking microscopy data of endogenous lipid granules in living fission yeast cells with analytical results we show evidence for anomalous diffusion and weak ergodicity breaking. Namely we demonstrate that at short times the granules perform subdiffusion according to the laws of continuous time random walk theory. The associated violation of ergodicity leads to a characteristic turnover between two scaling regimes of the time averaged mean squared displacement. At longer times the granule motion is consistent with fractional Brownian motion.

Globally baryon symmetric cosmology, GUT spontaneous symmetry breaking, and the structure of the universe

NASA Technical Reports Server (NTRS)

Stecker, F. W.; Brown, R. W.

1979-01-01

Grand unified theories (GUT) such as SU(5), with spontaneous symmetry breaking, can lead more naturally to a globally baryon symmetric big bang cosmology with a domain structure than to a totally asymmetric cosmology. The symmetry is broken at random in causally independent domains, favoring neither a baryon nor an antibaryon excess on a universal scale. Because of the additional freedom in the high-energy physics allowed by such GUT gauge theories, new observational tests may be possible. Arguments in favor of this cosmology and various observational tests are discussed.

History of electroweak symmetry breaking

NASA Astrophysics Data System (ADS)

Kibble, T. W. B.

2015-07-01

In this talk, I recall the history of the development of the unified electroweak theory, incorporating the symmetry-breaking Higgs mechanism, as I saw it from my standpoint as a member of Abdus Salam's group at Imperial College. I start by describing the state of physics in the years after the Second World War, explain how the goal of a unified gauge theory of weak and electromagnetic interactions emerged, the obstacles encountered, in particular the Goldstone theorem, and how they were overcome, followed by a brief account of more recent history, culminating in the historic discovery of the Higgs boson in 2012.

Laser Hole Boring into Overdense Plasma and Relativistic Electron Currents for Fast Ignition of ICF Targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pukhov, A.; Meyer-ter-Vehn, J.

Laser hole boring and relativistic electron transport into plasma of 10 times critical density is studied by means of 2D particle-in-cell simulation. At intensities of I{sub 0}{lambda}{sup 2}=10{sup 20} W(cm){sup {minus}2} {mu}m{sup 2}, a channel 12{lambda} deep and 3{lambda} in diameter has formed after 200 laser cycles. The laser driven electron current carries up to 40{percent} of the incident laser power. When penetrating the overdense region, it breaks up into several filaments at early times, but is channeled into a single magnetized jet later on. These features are essential for fast ignition of targets for inertial confinement fusion (ICF). {copyright}more » {ital 1997} {ital The American Physical Society}« less

Playing tricks to ions

NASA Astrophysics Data System (ADS)

Leibfried, Dietrich

2017-01-01

Ted Hänsch's career is defined by breaking new ground in experimental physics. Curiosity, vivid imagination, deep understanding, patience and tenacity are part of the winning formula, but perhaps an equally important ingredient may be Ted's favorite past-time of exploring new tricks in his "Spiellabor" (play-lab), that often resurfaced as key ingredients in rather serious experiments later. On the occasion of Ted's 75th birthday, a few past and potential future experiments with trapped ions are playfully surveyed here. Some of these tricks are already part of the trade, some are currently emerging and a few are mostly speculation today. Maybe some of the latter will be realized and even prove useful in the future.

Applicability of steady models for hot-star winds

NASA Technical Reports Server (NTRS)

Owocki, Stanley P.; Poe, Clint H.; Castor, John I.

1990-01-01

Non-Sobolev models of radiatively driven stellar winds based on a pure-absorption approximation do not have a well-defined steady state. Here the implications of this for flow time-dependence are examined, showing that, under such circumstances, instabilities in the flow attain an absolute character that leads to intrinsic variability. In this case, steady solutions are inherently inapplicable because they do not represent physically realizable states. However, for actual hot-star winds, driving is principally by scattering, not pure absorption. In practice, the relatively weak force associated with slight asymmetries in the diffuse, scattered radiation field may play a crucial role in breaking the solution degeneracy and reducing the instability from an absolute to an advective character.

Zero refractive index in time-Floquet acoustic metamaterials

NASA Astrophysics Data System (ADS)

Koutserimpas, Theodoros T.; Fleury, Romain

2018-03-01

New scientific investigations of artificially structured materials and experiments have exhibited wave manipulation to the extreme. In particular, zero refractive index metamaterials have been on the front line of wave physics research for their unique wave manipulation properties and application potentials. Remarkably, in such exotic materials, time-harmonic fields have an infinite wavelength and do not exhibit any spatial variations in their phase distribution. This unique feature can be achieved by forcing a Dirac cone to the center of the Brillouin zone ( Γ point), as previously predicted and experimentally demonstrated in time-invariant metamaterials by means of accidental degeneracy between three different modes. In this article, we propose a different approach that enables true conical dispersion at Γ with twofold degeneracy and generates zero index properties. We break time-reversal symmetry and exploit a time-Floquet modulation scheme to demonstrate a time-Floquet acoustic metamaterial with zero refractive index. This behavior, predicted using stroboscopic analysis, is confirmed by full-wave finite element simulations. Our results establish the relevance of time-Floquet metamaterials as a novel reconfigurable platform for wave control.

Modelling wave-induced sea ice break-up in the marginal ice zone

NASA Astrophysics Data System (ADS)

Montiel, F.; Squire, V. A.

2017-10-01

A model of ice floe break-up under ocean wave forcing in the marginal ice zone (MIZ) is proposed to investigate how floe size distribution (FSD) evolves under repeated wave break-up events. A three-dimensional linear model of ocean wave scattering by a finite array of compliant circular ice floes is coupled to a flexural failure model, which breaks a floe into two floes provided the two-dimensional stress field satisfies a break-up criterion. A closed-feedback loop algorithm is devised, which (i) solves the wave-scattering problem for a given FSD under time-harmonic plane wave forcing, (ii) computes the stress field in all the floes, (iii) fractures the floes satisfying the break-up criterion, and (iv) generates an updated FSD, initializing the geometry for the next iteration of the loop. The FSD after 50 break-up events is unimodal and near normal, or bimodal, suggesting waves alone do not govern the power law observed in some field studies. Multiple scattering is found to enhance break-up for long waves and thin ice, but to reduce break-up for short waves and thick ice. A break-up front marches forward in the latter regime, as wave-induced fracture weakens the ice cover, allowing waves to travel deeper into the MIZ.

Modelling wave-induced sea ice break-up in the marginal ice zone

PubMed Central

Squire, V. A.

2017-01-01

A model of ice floe break-up under ocean wave forcing in the marginal ice zone (MIZ) is proposed to investigate how floe size distribution (FSD) evolves under repeated wave break-up events. A three-dimensional linear model of ocean wave scattering by a finite array of compliant circular ice floes is coupled to a flexural failure model, which breaks a floe into two floes provided the two-dimensional stress field satisfies a break-up criterion. A closed-feedback loop algorithm is devised, which (i) solves the wave-scattering problem for a given FSD under time-harmonic plane wave forcing, (ii) computes the stress field in all the floes, (iii) fractures the floes satisfying the break-up criterion, and (iv) generates an updated FSD, initializing the geometry for the next iteration of the loop. The FSD after 50 break-up events is unimodal and near normal, or bimodal, suggesting waves alone do not govern the power law observed in some field studies. Multiple scattering is found to enhance break-up for long waves and thin ice, but to reduce break-up for short waves and thick ice. A break-up front marches forward in the latter regime, as wave-induced fracture weakens the ice cover, allowing waves to travel deeper into the MIZ. PMID:29118659

Modelling wave-induced sea ice break-up in the marginal ice zone.

PubMed

Montiel, F; Squire, V A

2017-10-01

A model of ice floe break-up under ocean wave forcing in the marginal ice zone (MIZ) is proposed to investigate how floe size distribution (FSD) evolves under repeated wave break-up events. A three-dimensional linear model of ocean wave scattering by a finite array of compliant circular ice floes is coupled to a flexural failure model, which breaks a floe into two floes provided the two-dimensional stress field satisfies a break-up criterion. A closed-feedback loop algorithm is devised, which (i) solves the wave-scattering problem for a given FSD under time-harmonic plane wave forcing, (ii) computes the stress field in all the floes, (iii) fractures the floes satisfying the break-up criterion, and (iv) generates an updated FSD, initializing the geometry for the next iteration of the loop. The FSD after 50 break-up events is unimodal and near normal, or bimodal, suggesting waves alone do not govern the power law observed in some field studies. Multiple scattering is found to enhance break-up for long waves and thin ice, but to reduce break-up for short waves and thick ice. A break-up front marches forward in the latter regime, as wave-induced fracture weakens the ice cover, allowing waves to travel deeper into the MIZ.

Break point on the auto-correlation function of Elsässer variable z- in the super-Alfvénic solar wind fluctuations

NASA Astrophysics Data System (ADS)

Wang, X.; Tu, C. Y.; He, J.; Wang, L.

2017-12-01

It has been a longstanding debate on what the nature of Elsässer variables z- observed in the Alfvénic solar wind is. It is widely believed that z- represents inward propagating Alfvén waves and undergoes non-linear interaction with z+ to produce energy cascade. However, z- variations sometimes show nature of convective structures. Here we present a new data analysis on z- autocorrelation functions to get some definite information on its nature. We find that there is usually a break point on the z- auto-correlation function when the fluctuations show nearly pure Alfvénicity. The break point observed by Helios-2 spacecraft near 0.3 AU is at the first time lag ( 81 s), where the autocorrelation coefficient has the value less than that at zero-time lag by a factor of more than 0.4. The autocorrelation function breaks also appear in the WIND observations near 1 AU. The z- autocorrelation function is separated by the break into two parts: fast decreasing part and slowly decreasing part, which cannot be described in a whole by an exponential formula. The breaks in the z- autocorrelation function may represent that the z- time series are composed of high-frequency white noise and low-frequency apparent structures, which correspond to the flat and steep parts of the function, respectively. This explanation is supported by a simple test with a superposition of an artificial random data series and a smoothed random data series. Since in many cases z- autocorrelation functions do not decrease very quickly at large time lag and cannot be considered as the Lanczos type, no reliable value for correlation-time can be derived. Our results showed that in these cases with high Alfvénicity, z- should not be considered as inward-propagating wave. The power-law spectrum of z+ should be made by fluid turbulence cascade process presented by Kolmogorov.

An experimental study of the job demand-control model with measures of heart rate variability and salivary alpha-amylase: Evidence of increased stress responses to increased break autonomy.

PubMed

O'Donnell, Emma; Landolt, Kathleen; Hazi, Agnes; Dragano, Nico; Wright, Bradley J

2015-01-01

We assessed in an experimental design whether the stress response towards a work task was moderated by the autonomy to choose a break during the assigned time to complete the task. This setting is defined in accordance with the theoretical framework of the job-demand-control (JDC) model of work related stress. The findings from naturalistic investigations of a stress-buffering effect of autonomy (or 'buffer hypothesis') are equivocal and the experimental evidence is limited, especially with relation to physiological indices of stress. Our objective was to investigate if increased autonomy in a particular domain (break time control) was related with adaptive physiology using objective physiological markers of stress; heart rate variability (HRV) and salivary alpha amylase (sAA). We used a within-subject design and the 60 female participants were randomly assigned to an autonomy (free timing of break) and standard conditions (fixed timing of break) of a word processing task in a simulated office environment in a random order. Participants reported increased perceptions of autonomy, no difference in demand and performed worse in the task in the break-time autonomy versus the standard condition. The results revealed support for the manipulation of increased autonomy, but in the opposing direction. Increased autonomy was related with dysregulated physiological reactivity, synonymous with typical increased stress responses. Potentially, our findings may indicate that autonomy is not necessary a resource but could become an additional stressor when it adds additional complexity while the amount of work (demands) remains unchanged. Further, our findings underscore the need to collect objective physiological evidence of stress to supplement self-reported information. Self-report biases may partially explain the inconsistent findings with the buffer hypothesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Breaking Off of Large Ice Masses From Hanging Glaciers

NASA Astrophysics Data System (ADS)

Pralong, A.; Funk, M.

In order to reduce damage to settlements or other installations (roads, railway, etc) and avoid loss of life, a forecast of the final failure time of ice masses is required. At present, the most promising approach for such a prediction is based on the regularity by which certain large ice masses accelerate prior to the instant of collapse. The lim- itation of this forecast lies in short-term irregularities and in the difficulties to obtain sufficiently accurate data. A better physical understanding of the breaking off process is required, in order to improve the forecasting method. Previous analyze has shown that a stepwise crack extension coupling with a viscous flow leads to the observed acceleration function. We propose another approach by considering a local damage evolution law (gener- alized Kachanow's law) coupled with Glen's flow law to simulate the spatial evolu- tion of damage in polycristalline ice, using a finite element computational model. The present study focuses on the transition from a diffuse to a localised damage reparti- tion occurring during the damage evolution. The influence of inhomogeneous initial conditions (inhomogeneity of the mechanical properties of ice, damage inhomogene- ity) and inhomogeneous boundary conditions on the damage repartition are especially investigated.

Graviweak Unification, Invisible Universe and Dark Energy

NASA Astrophysics Data System (ADS)

Das, C. R.; Laperashvili, L. V.; Tureanu, A.

2013-07-01

We consider a graviweak unification model with the assumption of the existence of a hidden (invisible) sector of our Universe, parallel to the visible world. This Hidden World (HW) is assumed to be a Mirror World (MW) with broken mirror parity. We start with a diffeomorphism invariant theory of a gauge field valued in a Lie algebra g, which is broken spontaneously to the direct sum of the space-time Lorentz algebra and the Yang-Mills algebra: ˜ {g} = {{su}}(2) (grav)L ⊕ {{su}}(2)L — in the ordinary world, and ˜ {g}' = {{su}}(2){' (grav)}R ⊕ {{su}}(2)'R — in the hidden world. Using an extension of the Plebanski action for general relativity, we recover the actions for gravity, SU(2) Yang-Mills and Higgs fields in both (visible and invisible) sectors of the Universe, and also the total action. After symmetry breaking, all physical constants, including the Newton's constants, cosmological constants, Yang-Mills couplings, and other parameters, are determined by a single parameter g present in the initial action, and by the Higgs VEVs. The dark energy problem of this model predicts a too large supersymmetric breaking scale (MSUSY 1010GeV), which is not within the reach of the LHC experiments.

Effect of γ-irradiation on the physical and mechanical properties of kefiran biopolymer film.

PubMed

Shahabi-Ghahfarrokhi, Iman; Khodaiyan, Faramarz; Mousavi, Mohammad; Yousefi, Hossein

2015-03-01

In this study, the effect of different γ-ray dosages (3, 6, and 9 kGy) on the functional properties of kefiran biopolymer was investigated. The obtained results showed that increasing γ-ray dosage brought about an increase in the tensile strength of film specimens up to three-times. However, elongation at break, and tensile energy to break of γ-irradiated kefiran films decreased in the wake of increasing γ-ray dosage. γ-Irradiation could improve surface hydrophobicity, sensitivity of kefiran film specimens to water, and water vapor permeability, but yellowness of films increased, simultaneously. XRD spectrum confirmed increased crystallinity of γ-irradiated films. Melting point of films was constant but glass transition temperature decreased drastically at high γ-ray dosage (9 kGy). ATR-FTIR analysis confirmed that γ-ray engendered no changes in chemical functional groups. According to the result, a mechanism was proposed to percept the effects of γ-irradiation on kefiran biopolymer and its role on the functional properties of kefiran film. Hence, the functional properties of kefiran films were depend on the ratio of cross-linkages between polymer chains and produced mono and disaccharide by γ-irradiation. Copyright © 2014 Elsevier B.V. All rights reserved.

Inversion symmetry breaking induced triply degenerate points in orderly arranged PtSeTe family materials

NASA Astrophysics Data System (ADS)

Xiao, R. C.; Cheung, C. H.; Gong, P. L.; Lu, W. J.; Si, J. G.; Sun, Y. P.

2018-06-01

k paths exactly with symmetry allow to find triply degenerate points (TDPs) in band structures. The paths that host the type-II Dirac points in PtSe2 family materials also have the spatial symmetry. However, due to Kramers degeneracy (the systems have both inversion symmetry and time reversal symmetry), the crossing points in them are Dirac ones. In this work, based on symmetry analysis, first-principles calculations, and method, we predict that PtSe2 family materials should undergo topological transitions if the inversion symmetry is broken, i.e. the Dirac fermions in PtSe2 family materials split into TDPs in PtSeTe family materials (PtSSe, PtSeTe, and PdSeTe) with orderly arranged S/Se (Se/Te). It is different from the case in high-energy physics that breaking inversion symmetry I leads to the splitting of Dirac fermion into Weyl fermions. We also address a possible method to achieve the orderly arranged in PtSeTe family materials in experiments. Our study provides a real example that Dirac points transform into TDPs, and is helpful to investigate the topological transition between Dirac fermions and TDP fermions.